I'm not completely clear, are you just referring to drop down options when editing a feature? Something like this:
If so, you can easily do this by adding coded value domains to the field in your feature layer. Reference this page for the workflow: Define attribute lists and ranges—ArcGIS Online Help | Documentation
Hello, Katherine and thanks for your response. I am referring to a drop-down menu in a configured pop up box. When a feature on a web map is clicked, the information pop-up box will have a field with a drop-down menu. In the attached image, for example, the "tag_name" field will be a drop-down menu.
As far as I know, pop-ups aren't really intended to be interactive like that. What is your intended purpose for the drop-down menu if not for using in edit mode?