Drop-Down or Select field option?

Do you have a specific question?

There are two approaches, assuming you want to develop a custom solution ( rather than use some plugin or other )

1. the ‘old’ way – write a shortcode – mainly PHP and relatively simple if you know PHP & HTML

2. the ‘new way’ – write a block -mainly javascript and quite complex to get to grips with initially

Ah you are in the wrong forum, not sure how you move

https://wordpress.org/support/topic/using-the-developing-with-wordpress-sub-forum/

If you are looking for a plugin recommendation, ask in the Fixing WordPress sub-forum instead

.