ScummVM aims for authenticity, so at least in its initial implementation the UI would most likely be exactly the same as it was at release, but it does open the door for modification I suppose - you may not see those enhancements made directly in the ScummVM tree though.
I've definitely seen engines with optional UI/QOL improvements included in ScummVM. Ultima VI, for instance, has a number of options that make it play a little closer to Ultima VII.
