RCS thrusters could also be used as a scaling tool. Plus, if the Excelsior has any docking rings for the travel pods, those are guaranteed to be identically sized, for obvious reasons. Windows may also be a tell, as the Excelsior has both circular and long rounded-edge windows, just like Enterprise. It is not outside the realm of reason to surmise that windows should be of a standard size across all Fed starships, at least of that era. They appeared bigger starting with the E-C, IIRC.