Perhaps he'll meet a rival. A student who is extremely talented in magic and sees Harry as a threat. This rival could constantly try to outdo Harry in every class and magical competition, creating a tense and competitive atmosphere for Harry.
He could meet a brilliant but eccentric teacher. This teacher might be an expert in a very rare branch of magic that Harry has never heard of before. The teacher could take Harry under their wing and teach him things that Dumbledore or the other Hogwarts teachers never did.
Well, he might make new friends. In a new school, Harry would be exposed to different students and personalities. He could meet a group of outcasts who are actually really powerful in magic but are shunned for some reason. They might form a secret club together to practice unique spells.
He could meet new witches and wizards from different cultures. For example, he might run into a powerful African wizard who has unique magical abilities related to nature magic. Or he could meet a Japanese witch who specializes in charm - making that is based on ancient Shinto beliefs.
Harry might meet some American wizarding families that have long - standing traditions different from the pure - blood families in the UK. These families could introduce Harry to new forms of magic and social norms within the American wizarding community. He could also meet American Muggle - born wizards who have their own unique stories of discovering magic in a different cultural context compared to what he's used to.
Perhaps he'll meet a mysterious old wizard who lives in a secluded temple in the mountains. This wizard could be a master of ancient Japanese magic and could teach Harry about the spiritual side of magic that is deeply ingrained in Japanese culture. Harry might also meet a group of young Japanese witches who are training to become magical healers. They could share their knowledge of Japanese magical plants and how to use them for healing, which would be very different from the healing methods Harry learned at Hogwarts.
He could meet Scott McCall. Scott, being a werewolf, would be intrigued by Harry's magic. They could become friends and learn from each other. Harry could help Scott better control his werewolf side using magic, and Scott could show Harry how to survive in Beacon Hills' supernatural chaos.
He could meet French pure - blood families who have their own long - standing traditions. For instance, there might be a family that has a special connection to a particular magical forest in France. Harry might also run into French wizards who are experts in potion - making, as France is known for its fine potions in the wizarding world.
There's a chance he meets some magical creatures that can talk in the American wilderness. For example, he might encounter a Sasquatch that has a deep understanding of the ancient magic in America. They could form an unlikely friendship and the Sasquatch could help Harry in his journey to adapt to the new magical environment.
Harry could meet students from Ilvermorny. They would have different personalities and magical abilities compared to Hogwarts students. He might also meet American magical creatures' caretakers who can introduce him to creatures like the Wampus cat or the Horned Serpent. Additionally, he could come across American Aurors who have their own methods of dealing with dark wizards.
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.