I looked (surfed) around a lot to get idea of how can I add custom field/drop-down under "Menu Settings" in WordPress Admin.

I want a select tag with options from which I can get value based on the current selected menu.

Below image shows the basic idea what I am trying to get:

I want this to associate value for each selected menu and get it for dynamic theme style for the menu.

P.S. I am new to WordPress Development, please bear me.

Your help would be really appreciated.

Thank You!