One possibility is that Naruto stumbles upon a hidden village in the wild that has been cut off from the rest of the ninja world for centuries. He has to learn their unique culture and way of life. This experience could shape his view of the ninja world in a new way. He might also find a powerful and mysterious mentor in the wild who teaches him skills that are different from what he would learn in Konoha, such as how to use natural elements in a more primal and instinctive way.
He could encounter rare mythical creatures that are only found in the deepest parts of the wild. For example, he might come across a group of centaurs who have a different culture compared to those he met before. These centaurs could teach him new survival skills and ancient lore.
One possibility is that he discovers an ancient, hidden grove that has a powerful magical spring. This spring could have the ability to heal any wound or grant temporary superhuman strength. Percy would then have to protect this grove from other forces that might want to use it for evil purposes.
Well, he might discover hidden caves filled with ancient treasures. Maybe he'll meet some unique dwarven craftsmen who teach him about their art.
He could go on adventures to find rare snakes that hold ancient secrets. Maybe there's a snake that knows the location of a powerful jutsu or a hidden treasure. He could also be called upon by a snake clan to help them solve a mystery within their lair, like a curse that's been plaguing them.
One possible reason could be a curse. Maybe Naruto got caught in some ancient jutsu or curse that was meant for someone else. For example, a dark ninja from the past might have placed a curse on a certain bloodline, and Naruto accidentally triggered it because of his own unique chakra nature. Another reason could be some sort of experiment gone wrong. Orochimaru was always doing strange experiments, and perhaps he had a hand in this, trying to create a new form of power using Naruto as a test subject. It could also be related to a new power that Naruto is developing on his own. As he grows and faces new challenges, his body might be mutating in this strange way to adapt to a greater power he is about to unlock.
He could have adventures trading with different villages. Maybe he'd discover rare ninja tools in a small, remote village and have to haggle with the local merchants to get a good deal. Then he'd bring those tools back to Konoha and sell them at a profit, all while facing rivals who are jealous of his new business.
He could be on a mission to protect the Hidden Leaf from a new and powerful enemy. Maybe he has to travel to far - off lands and use his enhanced skills, like his Rasengan, in new and creative ways.
They could team up to rescue a kidnapped ninja. The cat could track the kidnapper's scent, and Naruto could engage in combat when they find the enemy. Naruto's determination combined with the cat's stealth would make them a formidable duo in this rescue mission.
He could make new friends. For example, in a village like Suna, he might meet a young ninja with a unique sand - based jutsu. They could team up and face challenges together, like a new threat that is targeting both Konoha and Suna.
They could go on a quest to find a magical artifact that was lost in a forgotten temple. Percy could use his ability to breathe underwater to explore the flooded parts of the temple, while Steve could break through the stone walls and barriers. Another adventure could be facing a powerful dragon that was terrorizing a village. Percy could use his water powers to cool the dragon's fiery breath, and Steve could build traps to catch the dragon. Or perhaps they could explore an ancient forest filled with dangerous creatures. Percy would use his demigod senses to detect the threats, and Steve would use his axe to clear the way through the thick foliage.