I love kids animated movies personally.
Alicia would probably be a shy kid with social anxiety who just entered Junior High and is convinced she's going to have the worst year of her life. But she's really good at art, and that's her way of expressing herself. One day she meets Kattar who notices her art and thinks she's super cool and they instantly becomes best friends, he encourages her that she is talented and to put herself out there. Some big art competition comes up and he tells her she should try out for it though she's too scared to do something that daring. She applies, but then some mean kids steal her art submission and they have to go through a whole epic chase thing to get it back, maybe it gets lost altogether. There's an emotional conversation about how even if other people ditched you or gave up on you, that doesn't mean you have to give up on yourself. You have to show yourself that you're worth it. So with just a few days/hours left before the competition she makes a new piece which she submits to the competition and she probably wins.
And yes, there would probably be a celebrity voice actor, most likely someone like Jennifer Lopez would vice Mrs. Moon, and there would probably be a celebrity voicing Kattar as well. And a song made Alessia Cara. And it would be something I would rewatch a dozen times.