How Can I add a custom dropdown type field at the admin create order billing form in magento2

I want to convert the city text field in the dropdown field at the admin create order page. I had done the same thing in customer checkout using the Layououtprocessor plugin. Also, I did the thing in Admin customer add address form using UI component. But none of the concepts is working for the admin order create form.

Any help will be grateful. Thanks in advance.