Yes this really depends on what you want to achieve!
A dropdown menu for a developer would be a custom Enumerator. You can create these when you right click in the “ContentBrowser” where you normally click to create a new Blueprint, but instead of choosing BP,
you go to the ListEntry “Blueprints” and in the opening list, you choose “Enumeration”. You can the add several strings to it and later on select this Enumerator as a Variable type in your Blueprint.
If you want a dropdown menu for the Player, you will want to check out UMGs drop down menu!