His life could change drastically. He might start to see the magical world in a different light earlier than in the original. For example, he could meet some early allies or enemies right after getting the letter.
In fanfiction, when Harry Potter gets his letter at 9, it sets off a chain of events that alters his life significantly. The letter could be a signal to certain magical beings that Harry is now 'in the game' so to speak. This might lead to him being visited by various wizards or witches who want to either help or hinder him. He may also start to question his place in the muggle world more quickly as he is thrust into the knowledge of the magical world at an earlier age, which in turn could affect his relationships with his muggle family and friends.
The phoenix could give Harry a sense of purpose. Knowing he has such a powerful and magical creature by his side, he might feel more confident. For instance, he could be more daring in his adventures and face his enemies without as much fear.
Well, it would change his life drastically. Firstly, he'd be in a completely different cultural and magical setting. Kuroka's world likely has different magic rules and social norms. Harry would probably learn new magic skills that are unique to that world. Also, he'd be away from the Dursleys and the whole Voldemort threat in the wizarding world he originally knew. He might form new relationships with the characters in Kuroka's world and grow up with a different set of values.
In some fanfictions, when Harry Potter gets his letter at 9, it might be a moment of great excitement. It could be the start of his journey into the wizarding world just like in the original story, but with some unique twists added by the fanfiction author. Maybe the owl that delivers the letter has some special markings or behaves in an unexpected way.
Harry's social circle would expand in a very different way. He'd be introduced to the other sorcerers and strange beings that Dr. Strange knows. This could be both exciting and a bit intimidating for Harry. He might also have to deal with new enemies that come from the threats in Dr. Strange's world, which would be a whole new level of danger compared to what he faced at Hogwarts.
His life would change drastically. He'd be surrounded by magic instead of ninjutsu. He might go to Hogwarts and have to study subjects like Transfiguration and Defence Against the Dark Arts. His daily routine would be completely different, from waking up in a dormitory to having meals in the Great Hall. He'd also have to follow the wizarding laws, which are very different from the laws in the ninja villages.
It might make him more aware of his family's past and connections. If the letter reveals something about his family's wealth or status, it could change how others view him.
The Potter ring might have some sort of magical essence that enhances Harry's natural abilities. Maybe it gives him extra strength or speed when he's in a fight. The grimoire, full of rare spells and knowledge, could change the way Harry approaches magic. He might become more experimental and less reliant on the traditional spells he learned at Hogwarts. This could make him a more unpredictable and formidable opponent to his enemies.
It could change his life by giving him a new form of magic. For example, he might be able to combine the power of the stand with his existing magic, making his spells more powerful.
His living conditions would change drastically. Instead of living in the wizarding world, he'd be in palaces. He'd have servants and all the luxuries that come with royalty. His friends at Hogwarts would be replaced by new acquaintances in the royal circle. He'd have to adapt to a very different set of rules and expectations.
The learning trunk might offer him a more personalized learning experience. For example, if he's struggling with a certain spell, the trunk could provide a step - by - step guide or even a magical tutor in the form of a spell - casted projection. Also, it could give him the opportunity to study at his own pace without the distractions of a classroom. He can focus on the areas he's most interested in or needs to improve on, like advanced transfiguration or advanced defense against the dark arts.