The Rinnegan is revered as the strongest of all the Dōjutsu. Very few people have managed to awaken the Rinnegan in Naruto, which has left the fans wondering how a person gains the Rinnegan.
First, I’m gonna explain a few things about the Rinnegan. It was first manifested in the eyes of Hagoromo Ōtsutsuki through Kaguya’s Rinne-Sharingan.
So in reality, it was the result of a mutation, just like the Sharingan.
The Rinnegan wasn’t as powerful as the Rinne-Sharingan, but was strong enough to reshape the planet, when coupled with the Six Paths Chakra.
Rinnegan granted the user such strong abilities, that any user of the Rinnegan was regarded as a ‘God’.