Submenu Item defined by Drop Down Menu

Is there any current automations in place, to where if you select an item in a drop down menu that it will auto populate sub menu list item(s)? For example, (I’m a mortgage lender), so if I selected FHA in the drop down menu, Id like to see the submenu items populate with a list of required documents that I specify for that loan program. Currently if I select a button, it will populate with my list based on automation, but I don’t want to have several different buttons for each loan program. Id rather select from a drop down list.

Didn’t know if this was possible, or if anyone had any thoughts?

Thank you in advance!