Indra got the Sage's eyes and was gifted with powerful chakra and spiritual energy (Yin) and Ashura got the Sage body and was gifted with lifeforce and physical energy (Yang)
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. Hagaromo made Sasuke like Indra with his Yin chakra and Naruto like Ashura with his Yang. Yin= eyes yang= body when it comes to Indra reincarnations and Ashura reincarnations. Madara was said to be born with very powerful chakra even among the Uchihas and Sasuke's chakra was compared to Madara's by Kurama and Madara mentions how Sasuke have straight comas like him more than once. No other way for Sasuke to get the Rinnegan but Hagaromo as Hagaromo already said Madara only got the Rinnegan because he got a Hashirama's cells before the transmigration was over and it's currently Naruto who is Ashura's reincarnation.