Sasuke Uchiha is one of the most important characters in the world of Naruto, along with the protagonist of the series, Naruto Uzumaki. Born as a genius of the Uchiha clan, Sasuke was blessed with the power of the Sharingan and was destined to achieve great things as a ninja. With the eyes of his clan and a keen mind to put them to the very best use, Sasuke progressed immensely through the years and ended up becoming one of the very strongest characters by the end of the Fourth Great Ninja War.
Over the years, Sasuke received multiple power-ups such as the Cursed Seal, the Mangekyo Sharingan, and even the Eternal Mangekyo Sharingan, however, no power-up was as big for him as the godly eye of the Rinnegan that he finally received in the Fourth Great Ninja War.
How Sasuke Awakened The Rinnegan
The Rinnegan is one of the Three Great Eyes in the Naruto world - the other two being the Sharingan and the Byakugan. Out of all three, the Rinnegan is, by far, the strongest eye and is known to only awaken in people who greatly alter the fate of the world. One with the Rinnegan is known to shape the world in drastic ways, that is, either bring peace and harmony to the world or send it into utter chaos. For Sasuke Uchiha to receive this just goes to show how important his character was to Masashi Kishimoto. As he's stated on several occasions, Sasuke and Naruto and the two sides of the same coin. Often, he makes them progress side by side and Sasuke has also been described to be the Yin to Naruto's Yang. As Naruto received the power of the Six Paths Sage Mode, Sasuke received the Rinnegan as an equivalent upgrade.
The Rinnegan isn't all that easy to acquire, however. In fact, in all of Naruto, only three people are known to have awakened this power. Originally, the Rinnegan belonged to the Sage of Six Paths, Hagoromo Otsutsuki. He inherited this eye from his mother, Kaguya Otsutsuki, who had the Rinne Sharingan, a Kekkei Mora related to both the Sharingan and the Rinnegan. Hagoromo's son, Indra Otsutsuki, inherited his visual prowess as the Sharingan and became the founder of the Uchiha clan. As such, the Uchiha were his descendants and all had a piece of the power of the Sage of Six Paths.
To awaken the Rinnegan, however, one would need to combine the power of both of Hagoromo's sons to give rise to his own chakra. As such, awakening the Rinnegan is only possible for their reincarnations, or someone making use of their chakra. Madara Uchiha became the first person to awaken this eye when he was Indra's reincarnation. He stole Hashirama's flesh, who was Asura's reincarnation, and the combination of these two powers led to the awakening of the Rinnegan. In the Fourth Great Ninja War, Sasuke Uchiha, who was already the reincarnation of Indra Otsutsuki, met Hagoromo after he was in a near-death state. Just as with Naruto, Hagoromo gave half of his chakra to Sasuke, which led to his left Sharingan turning into a Rinnegan.
The Powers Of Sasuke's Rinnegan
The Rinnegan is an almighty Dojutsu known to be the strongest of all the Three Great Dojutsu. Being the eye of a god, it's no surprise that Sasuke's Rinnegan is extremely overpowered. Aside from granting the power to basically master any jutsu and nature transformations, every Rinnegan user has access to a basic six powers called the Six Paths powers. These Six Paths include the usage of the King of Hell through the Naraka Path; the ability to control attraction and repulsion through the Deva Path; the power to summon animals using the Animal Path; the power to create weaponry from one's body using Asura Path; absorbing all forms of chakra using Preta Path; and finally, the power to extract souls using the Human Path. Evidently, the Rinnegan is an eye with many powers to offer but it doesn't just stop there. To all Rinnegan users, a Seventh Path is also available, and this one is known to rule over life and death itself. As such, Sasuke's Rinnegan also grants him this majestic power with the Outer Path. In other words, he can bring people back from death if he so wishes.
By the looks of it, every user of the Rinnegan also gets a unique ability, and Sasuke's case is no different. His Rinnegan possesses unique six tomoes, suggesting greater ocular powers. In combat, Sasuke can make use of an ability called Amenotekikara, which allows him to swap the places of two objects instantly within a certain range. Over the years, Sasuke has mastered this ability to a great extent and has learned how to swap anything and everything with himself. Furthermore, Sasuke can also open portals to different dimensions using his Rinnegan, however, this jutsu takes up a lot of chakra for him and he only learned it at some point during the timeskip after the end of the story. Unfortunately, Sasuke Uchiha's Rinnegan was stabbed by Boruto Uzumaki in the continuation of Naruto, Boruto: Naruto Next Generations. Whether he will ever have access to this eye again remains to be seen, however, for now, Sasuke is without his biggest power to aid him in battle.