Revit has a 'soffit' wall. It's a wall type that is drawn *downwards* from the current level to a depth that's user-defined and allows for any kind of construction you might want (just like all the other walls). So then it's construction could be vertical t-bar or whatever.
So switch to an RCP, set the 'base offset', levels, and 'top offset' to jive with your ceiling vs. slab heights, and then draw your bulkhead. Better than an in-place family for then Revit know they are walls, and will deal with them as such, and allow you to change them very easily....