A large majority of all choices affect something, but there are a few that are just for flare, or cosmetic like you said. I don't want to spoil any actual choices, but for example there is one choice that deals with the mc's morality, but doesn't have any long-lasting effects. At least for now. 😉
And don't worry—getting those "bad endings" first is a proud visual novel tradition for the few honest players! 😅