i think building from their role in the story is a good thing to start with, as thats gonna be the pathway of their character arc
say, for example... marlin from finding nemo. his role in the story is to go on a search across the ocean to find his son - if marlon was a swashbuckling adventurer who did this kind of thing on the reg, there would be no conflict or tension. so lets go for the opposite - marlin is an agoraphobic, clingy worrywart who associates the open ocean with great loss. this creates tension as he has to overcome his greatest fear throughout the story. his personality also rubs against the other characters, so defining marlin as a worrywart means everyone around him can be characterised by his opposites; dory is a carefree flake, creating conflict between the two and a comedic balance, nemo is rebellious and stubborn, contrasting with marlin's control freak personality and creating the primary conflict and eachothers character arc. it all stems from what pushes the characters within your story - what kind of seaweed marlin likes to eat? not really relevant.
when it comes to things like their demeanor and tastes, this should also be used to communicate their central traits, the ones that push the story. daria from darias entire conflict is her status as an outsider, so that bleeds through in her costume design, room design, voice, and posture - all very utilitarian and dull compared to the frivolity and colour of her sister and peers.
that said, when developing my characters a lot is on instinct - i tailor my characters to fit their roles and consider their character arcs, but also need to let them ruminate in my head for a few weeks in some theoretical scenarios to get a feel for how they talk, move, and react.