"Depends on the size the animal normally is, from what I've seen. But I haven't seen too many in the first place," he says. "You mean, like, if someone had a mouse devil fruit, would they be the size of a mouse when in that form? Probably."

Which is strange, regardless of what Gregor is thinking. Where does all the extra... body stuff go? Do the cells themselves shrink down? Way outside his wheelhouse. When Sengoku goes all golden Buddha, does he draw material in from around him to sustain the enormous size increase? Can't say he ever thought to ask, since the man didn't exactly go parading around like that, saving it only for dire circumstances.