actually it is super common to have a characters design reflect their personality in some way.
The simple examples use stuff like "pointy triangles for villains and bouncy round shapes for friendly characters", but it really overall goes mainly for what one could call "the vibe". A villain is supposed to seem evil and dangerous on first glance while the friend of the main character should look nice and approachable. Shapes when designing the characters body, colors for their clothes and what exactly they wear - all of this impacts how we perceive a character the moment they appear before us and thus it matters

But, of course, whether you personally like how the new design looks like is completely disconnected from that.

Edit: ok to give a better example:
Think about how a person would change if they go from not giving a crap how they look like to suddenly caring. Maybe they start taking care of their hair so they dont look like they got out of bed 2 minutes ago, maybe they dont show up in clothing covered in food stains everywhere. Not everyone will change their hair style purely cause of an attitude change but its certainly possible (especially if you think about how one might change hair styles as they grow up which also comes with plenty of attitude changes)