He could meet the Dalton students. They might be very different from his Hogwarts friends, maybe more focused on academic magic in a different way.
He could meet an Egyptian wizard who is an expert in ancient magic. This wizard could teach Harry a great deal about the history of magic in Egypt.
Well, perhaps Harry Potter goes to Dalton and discovers a whole new world of magic there. Maybe he meets new friends and has to face different challenges compared to Hogwarts.
He might meet Canadian witches and wizards. There could be a friendly wizard who shows him around the Canadian wizarding community.
He might meet international aurors. These are highly skilled wizards from different countries who are experts in dark wizard catching. They could teach Harry some new combat spells.
He could meet Fleur Delacour's family. Since Fleur is from France, her family might be an important part of the French wizarding community that Harry interacts with.
Harry could meet some local magical creatures that are unique to Africa. For example, there could be a magical creature similar to a hippogriff but with different characteristics. And he may also meet African witches who are experts in herbal magic, which they use to heal and protect their communities. They could teach Harry some of their techniques and knowledge.
He could meet new professors. These professors would have their own teaching styles and areas of expertise. They might introduce Harry to different aspects of American magic that he has never encountered before.
He could also meet some sort of dark wizard or villain that is even more powerful than Voldemort in this new world. This would pose a great threat to Harry and force him to use all of his skills and knowledge, both from his own world and what he's learned in the new one, to defeat the enemy.
He might meet other Hogwarts students who he doesn't know very well. They could become good friends through their shared love of Quidditch.
She might meet a powerful and mysterious wizard who has been hiding in Vegas for a long time. This wizard could be either a potential ally or an enemy. There could also be a group of young witches and wizards who are having their own adventures in Vegas and they all team up with fem Harry Potter for a wild ride full of magic, mystery, and fun.