There's an easy and somewhat lazy solution. Multiverse it. Let the character go to Diagon Alley to get all of their first year supplies then when crossing the platform your character somehow enters an alternate reality of the wizarding world by means of something going terribly wrong. Doing this could even have you attend Hogwarts in the same time as Harry, if they wanted to go that direction of course. Either way that would let them introduce a new big bad or allow you to actually be involved with something large scale in that alternate timeline.
Me personally I just want to go to classes to unlock spells and upgrades and get mixed up in various side quests in Hogwarts but also some out in the world. I would also love to go for all of the years and see your character grow up a little each year. Hogwarts Legacy had you leaving so often which felt out of place as in the books/movies they were always having to sneak around outside of their studies.
I loved the game and wasn't too upset about not having quidditch in the game. I wished that they at least had games that we could observe though as not every student is chosen for the game. I look forward to the sequel, hopefully they add at least optional co-op to it. It's always fun to play with a loved one or small group of friends.
