If you are looking at a bottom level object (group or component), the contents, which would be raw geometry should be untagged. ALL edges and faces should be untagged. If you have a nested object; one containing other objects, those objects might be untagged or they might have tags. That’s up to you. They won’t automatically get those tags, though.
In the case of nested objects you might give the top level object one tag and the objects inside it other tags. Maybe you have a group for the first floor walls, and then you have doors and windows. The walls could have a tag, the doors, another tag, and the windows a third tag. Then you could select all of those objects and make a group which you give a “first floor” tag.
Since the addition of tag folders, you could skip the nesting, though, and create a First Floor folder that contains the wall, doors, and windows tags.
If you tag the raw geometry you create more work for yourself than you need to and you open yourself up for creating errors and a general nighmare in model management. There’s no reason to tag the geometry and it makes your workflow much easier and cleaner. This isn’t anything new. It’s the same workflow as with the older versions that call them layers instead of tags.