What is the best way to save a custom field in shipping address?

Question

I have added a custom field on checkout in shipping address section using below code.

etc/frontend/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Checkout\Block\Checkout\LayoutProcessor">
        <plugin name="ProcessAddressConfiguration" type="Vendor\Module\Block\Checkout\PassportProcessor"/>
    </type>
</config>

Block/Checkout/PassportProcessor.php

<?php
namespace Vendor\Module\Block\Checkout;

class PassportProcessor
{
    public function afterProcess(\Magento\Checkout\Block\Checkout\LayoutProcessor $processor, $jsLayout){

        $passport_no = 'passport_no';

        $newField = [
            'component' => 'Magento_Ui/js/form/element/abstract',
            'config' => [
                'customScope' => 'shippingAddress.custom_attributes',
                'customEntry' => null,
                'template' => 'ui/form/field',
                'elementTmpl' => 'ui/form/element/input',
                'tooltip' => [
                    'description' => 'description'
                ]
            ],
            'dataScope' => 'shippingAddress.custom_attributes.' . $passport_no,
            'label' => 'Passport Number',
            'provider' => 'checkoutProvider',
            'sortOrder' => 0,
            'validation' => [
                'required-entry' => true
            ],
            'options' => [],
            'filterBy' => null,
            'customEntry' => null,
            'visible' => true
        ];

        $jsLayout['components']['checkout']['children']['steps']['children']['shipping-step']['children']['shippingAddress']['children']['shipping-address-fieldset']['children'][$passport_no] = $newField;

        return $jsLayout;
    }
}

Questions:

• In which tables I should save it so that when I pull the order, passport_no should be available in shipping address section of that order?
• How I can save passport_no in those tables from here?

I went through multiple posts but I do not see a complete list of steps which should be taken to achieve it.