Random thing I want to mention, in Smash Ultimate, the Inkling intro animation shows a grey squid jumping into the ink color of the costume you choose, and then going into kid form as the costume you picked, so I believe they are able to change it.
I don’t think that evidence is good to use because it comes from Smash Bros. And the series has a lot of inconsistencies with game series representation. Most of that does come from third-party games but we shouldn’t really use smash Bros as evidence for these kind of things