He could develop the ability to use the Six Paths Sage Mode more effectively. Since the Rinnegan is related to the Sage of Six Paths, it would enhance his connection to that power. He might also gain the ability to create chakra chains similar to those of the Uzumaki clan but with an added Rinnegan - powered twist.
Well, with the Rinnegan, Naruto might be able to access new dimensions. The Rinnegan has shown the ability to open portals to other realms. So, Naruto could explore these dimensions, perhaps find new sources of chakra or even new allies. He could also develop an enhanced form of his Rasengan. Maybe he could infuse it with Rinnegan - based chakra, making it more powerful and having different effects like being able to disrupt an opponent's chakra system on a deeper level.
He could develop the ability to use the Preta Path more effectively. This path allows the user to absorb chakra, and Naruto could use it to nullify enemy attacks that rely on chakra. For instance, if an enemy uses a powerful fire - style jutsu that is chakra - based, Naruto could absorb the chakra of the attack, rendering it useless.
He could have the ability to use all six paths techniques right from the start. This means he could manipulate gravity like the Deva Path, absorb chakra like the Preta Path, and even revive the dead like the Outer Path.
Maybe he would gain the ability to control the life force of others in a new way. With the red Rinnegan, Naruto could potentially heal or harm on a much greater scale. He could revive the recently deceased by restoring their life force, or he could drain the life force of his enemies to weaken them. This would be a huge shift from his normal abilities and add a new moral dimension to his character as he decides when and how to use such a power.
He might gain the ability to see chakra in a more detailed way. Since the Rinnegan is known for its enhanced visual perception of chakra, Naruto could use this to his advantage when dealing with Kurama's chakra. He could also potentially use the Rinnegan's power to enter Kurama's mindscape in a new way, maybe with more control and understanding. Another possible ability is to transfer Kurama's chakra to others in a more efficient and controlled manner using the powers of the Rinnegan.
Naruto would likely gain the ability to use all six paths techniques. The Rinnegan allows the user to manipulate gravity, as seen when Madara used it. Naruto could use this to enhance his combat skills, for example, pulling enemies towards him or pushing them away forcefully. He could also use the Preta Path to absorb chakra, which would be a great addition to his already large chakra reserves.
He could develop the ability to combine the power of the Sharingan with the Nine - Tails' chakra. Maybe he could use the Sharingan to better control the Nine - Tails' power, for instance, seeing the flow of the chakra inside him more clearly. This could lead to new jutsu that are a fusion of Uchiha and Uzumaki techniques.
He could perform powerful genjutsu with the Sharingan. Naruto, who was not really known for genjutsu before, would now be able to create illusions that are difficult to break. With the Rinnegan, he might be able to use the Six Paths techniques, like the ability to control gravity or absorb chakra attacks.
With the Rinnegan, Naruto might gain the power of the Human Path. This would allow him to read minds or rip out souls, which is a very dark and powerful ability that would be quite different from his usual positive - natured powers.
With the Rinnegan, he could have abilities like the Six Paths techniques. He might be able to use the Preta Path to absorb chakra attacks. And with the Hyoton, he could create ice - based jutsu that are much more powerful than normal ice jutsu, like freezing an entire area instantly.
He could develop the ability to better withstand the different climates in One Piece. Since he's immortal, he might experiment with his body in ways others can't. Maybe he could learn to breathe underwater like a fish - man over time due to his long - lasting life.