Like if you go full tadpole as a Gnome, do you end up as a pint sized Illithid?
I just thought about this, and if so I need to start a new playthrough immediately!
Yes but also no. Ceremorphosis only truly succeeds on certain kinds of species, generally only those of the human sized variety and a few kinds of monster. Gnomes can be technically transformed but only through heavy magic manipulation and there is still a chance of failure. All others just die along with the tadpole
Example here:
In D&D Faerun canon? I’m not sure.
In BG3, I’d wager that they all use the same illithid model.
I seem to recall in Act 3 after a certain point:
Tap for spoiler
Seeing random citizens all getting transformed after having all the macguffins when I fast travelled. Gnomes and dwarves both got the tall illithid model.