You have to use extension attribute to expose door number at reset Api.
- https://store.fooman.co.nz/blog/an-introduction-to-extension-attributes.html
- https://devdocs.magento.com/guides/v2.4/extension-dev-guide/extension_attributes/adding-attributes.html
Create an extension attribute on Magento\Sales\Api\Data\OrderAddressInterface for door no field.
Create extension_attributes.xml at app/code/{Vendorname}/{ModuleName}/etc
and add door number is an extension attributes.
<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
<extension_attributes for="Magento\Sales\Api\Data\OrderAddressInterface">
<attribute code="door_no" type="string" />
</extension_attributes>
</config>
I assume that door no is varchar field at the database level.
After that, need to expose this field to using a plugin on