He might use the spells to fight off evil creatures.
Well, he could accidentally cast a wrong spell and turn himself into a toad. Then he'd have to find a counter - spell in the book to turn himself back. Or he could use the magic spells to create amazing things like a floating castle or a magical garden filled with plants that can talk.
He might use the spells to fight off evil monsters. For example, if there are dragons threatening his village, he could use a spell to make them fall asleep.
It will make his life more exciting. He'll no longer be an ordinary boy.
In this fanfiction, Naruto might use the magic book to gain new powers. Maybe the book contains spells that can enhance his jutsu.
Well, it could be that the magic book is sentient and starts to communicate with Harry. It could offer him advice on how to defeat Voldemort in a completely new way, like revealing a long - forgotten prophecy.
Well, Naruto finding a baby boy in a fanfiction could lead to all sorts of adventures. Maybe the baby has some special power or is a key to some mystery in the Naruto world. Naruto would then have to protect the baby from those who would want to use the baby's power for evil.
Well, it depends on the context. If he's in a place where he has some free time, like in his dormitory, he could immerse himself in the fanfiction. He could share it with his friends too, especially Hermione who would probably be interested in analyzing the old magic described in it. And who knows, it might even inspire him to try out some new magical ideas in a safe way, perhaps during one of their magic practice sessions.
His life would become full of adventures.
No. Such a combination involves inappropriate and often not a mainstream or common literary genre. Most literature focuses on more positive, ethical and family - friendly themes.
I'm not sure if it's a particularly popular genre. While fantasy is a very popular genre overall, the combination of sexual magic spells in a story might be more niche and perhaps not as widely embraced in mainstream literature due to its potentially controversial nature.
In this fanfiction, perhaps the ancient book leads Naruto on a new adventure. It could be that the book has a connection to an ancient clan, and Naruto has to uncover the truth about that clan while also dealing with the power or knowledge the book holds. For example, the book might have a map to a hidden place full of valuable resources or training opportunities. He would then have to figure out how to get there and what to do with what he finds.