How to sort billing address fields in checkout page

Source taken from: https://magento.stackexchange.com/questions/163408/how-to-change-the-order-of-the-billing-address-fields-on-checkout-page-in-magent

Here is an example (using Plugin) for changing field order, disabling field or adding missing field to address.

File: etc/di.xml

<type name="Magento\Checkout\Block\Checkout\LayoutProcessor">
    <plugin disabled="false" name="Vendor_Module_Plugin_Block_Checkout_LayoutProcessor" sortOrder="99"
                type="Vendor\Module\Plugin\Block\Checkout\LayoutProcessor"/>
</type>

File: Plugin/Block/Checkout/LayoutProcessor.php

<?php

namespace Vendor\Module\Plugin\Block\Checkout;

use Magento\Checkout\Block\Checkout\LayoutProcessor as MageLayoutProcessor;

class LayoutProcessor
{
    public function afterProcess(MageLayoutProcessor $subject, $jsLayout)
    {

        /* config: checkout/options/display_billing_address_on = payment_method */
        if (isset($jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
            ['payment']['children']['payments-list']['children']
        )) {

            foreach ($jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                     ['payment']['children']['payments-list']['children'] as $key => $payment) {

                /* company */
                if (isset($payment['children']['form-fields']['children']['company'])) {

                    $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                    ['payment']['children']['payments-list']['children'][$key]['children']['form-fields']['children']
                    ['company']['sortOrder'] = 0;
                }

                /* region & region_id */
                if (isset($payment['children']['form-fields']['children']['region'])) {

                    $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                    ['payment']['children']['payments-list']['children'][$key]['children']['form-fields']['children']
                    ['region']['visible'] = false;

                    $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                    ['payment']['children']['payments-list']['children'][$key]['children']['form-fields']['children']
                    ['region']['config']['componentDisabled'] = true;
                }
                if (isset($payment['children']['form-fields']['children']['region_id'])) {

                    $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                    ['payment']['children']['payments-list']['children'][$key]['children']['form-fields']['children']
                    ['region_id']['visible'] = false;

                    $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                    ['payment']['children']['payments-list']['children'][$key]['children']['form-fields']['children']
                    ['region_id']['config']['componentDisabled'] = true;
                }

                $method = substr($key, 0, -5);

                /* vat_id */
                $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                ['payment']['children']['payments-list']['children'][$key]['children']['form-fields']['children']
                ['vat_id'] = [
                    'component' => 'Magento_Ui/js/form/element/abstract',
                    'config' => [
                        'customScope' => 'billingAddress' . $method,
                        'customEntry' => null,
                        'template' => 'ui/form/field',
                        'elementTmpl' => 'ui/form/element/input',
                        'tooltip' => null,
                    ],
                    'dataScope' => 'billingAddress' . $method . '.vat_id',
                    'dataScopePrefix' => 'billingAddress' . $method,
                    'label' => __('VAT number'),
                    'provider' => 'checkoutProvider',
                    'sortOrder' => 1,
                    'validation' => [],
                    'options' => [],
                    'filterBy' => null,
                    'customEntry' => null,
                    'visible' => true,
                ];
            }
        }

        /* config: checkout/options/display_billing_address_on = payment_page */
        if (isset($jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
            ['payment']['children']['afterMethods']['children']['billing-address-form']
        )) {

            /* company */
            if (isset($jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                ['payment']['children']['afterMethods']['children']['billing-address-form']['children']['form-fields']
                ['children']['company']
            )) {
                $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                ['payment']['children']['afterMethods']['children']['billing-address-form']['children']['form-fields']
                ['children']['company']['sortOrder'] = 0;
            }

            /* region & region_id */
            if (isset($jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                ['payment']['children']['afterMethods']['children']['billing-address-form']['children']['form-fields']
                ['children']['region'])) {

                $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                ['payment']['children']['afterMethods']['children']['billing-address-form']['children']['form-fields']
                ['children']['region']['visible'] = false;

                $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                ['payment']['children']['afterMethods']['children']['billing-address-form']['children']['form-fields']
                ['children']['region']['config']['componentDisabled'] = true;
            }
            if (isset($jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                ['payment']['children']['afterMethods']['children']['billing-address-form']['children']['form-fields']
                ['children']['region_id'])) {

                $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                ['payment']['children']['afterMethods']['children']['billing-address-form']['children']['form-fields']
                ['children']['region_id']['visible'] = false;

                $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
                ['payment']['children']['afterMethods']['children']['billing-address-form']['children']['form-fields']
                ['children']['region_id']['config']['componentDisabled'] = true;
            }

            $method = 'shared';

            /* vat_id */
            $jsLayout['components']['checkout']['children']['steps']['children']['billing-step']['children']
            ['payment']['children']['afterMethods']['children']['billing-address-form']['children']['form-fields']
            ['children']['vat_id'] = [
                'component' => 'Magento_Ui/js/form/element/abstract',
                'config' => [
                    'customScope' => 'billingAddress' . $method,
                    'customEntry' => null,
                    'template' => 'ui/form/field',
                    'elementTmpl' => 'ui/form/element/input',
                    'tooltip' => null,
                ],
                'dataScope' => 'billingAddress' . $method . '.vat_id',
                'dataScopePrefix' => 'billingAddress' . $method,
                'label' => __('VAT number'),
                'provider' => 'checkoutProvider',
                'sortOrder' => 1,
                'validation' => [],
                'options' => [],
                'filterBy' => null,
                'customEntry' => null,
                'visible' => true,
            ];
        }

        return $jsLayout;
    }
}