Situation number one Naturo would mysteriously create a Rinnegan from the moment he was born. This would make him far more likely to be the Child of Prophecy to Jiraiya, and he might be addressed by Jiraiya much sooner than in the original (thus learning Summoning Jutsu/Rasengan much sooner).
So What if Naruto had Rinnegan
Naruto would most likely be able to master all five natures in a year or two, and in terms of battle, he would be leagues ahead of everyone else in the Academy, including the teachers. Right off the start, he’d be Jonin level+. The only drawback is that he is utterly unaware of the Rinnegan’s abilities Chibaku Tensei, Shinra Tensei, and so on), which he would have to manifest and learn.
Moreover, the following are a few modifications to the plot that would most likely occur now that he has the Rinnegan. With no Nine Tails cheater amps, he’d wipe the floor with Haku.
In the Chunin Exams, he’d put up a much better fight against Orochimaru, but I’m going to suggest Sasuke still obtains the Curse Mark. Naruto would also not be knocked out.
He’d wipe the floor with the three Sound Ninja who had arrived to apprehend Sasuke. He would stomp every single person he met in the Chunin Exam bouts, including Lee because Lee would want to engage Naruto instead of Sasuke (for the supreme dojutsu thing and all).
During their combat, he would undoubtedly destroy Gaara. He’d put up a decent battle in the hotel against Itachi, but Itachi would still win since he’s Solo King. Above all, he would defeat Sasuke and resurrect him.
Situation number two Once Nagato completes the Rinne Rebirth, Nagato will tell Naruto to take his Rinnegan, which Naruto will do. Naruto is easily Kage Level at this time, having defeated a High Kage Level opponent (I know that was only due to some good old Nine-Tails cheater juice, but whatever). Because Naruto has already witnessed Rinnegan’s abilities in action, the disadvantage I outlined in the previous scenario isn’t present now (During his fight with pain).
In addition, Naruto would defeat most of the War opponents with little to no trouble, when in the original, he defeated them with medium to high difficulty. In my perspective, Sage Mode Naruto + Rinnegan + KCM could easily defeat Alive Hashirama.
Situation number three Hagoromo gives Naruto the Rinnegan, as well as his Six Paths abilities. This is by far the most likely of the three possibilities. Naruto could most likely solo Madara with the Rinnegan and SPSM, even with Sasuke, Sakura, and Kakashi there. For obvious reasons, the negative in this case is also non-existent. Because Naruto would have already destroyed him, there would be no Ze tsu-killing-Madara-and-using-him-to-resurrect-Kaguya scenario. The story comes to a close.
The series has come to an end. That’s the end of it. If Naruto wanted to, he could simply wipe off all life on Earth, including S Sasuke.