Nowhere this has been stated, so far the only thing that has been shown is that Madara can switch from EMS to Rinnegan and apparently the proper way to use Rinnegan is via combining it with EMS. However people are acting like if its just another stage from the same doujutsu just like 3 tomoe is to MS and so on and basically going like "Sasuke is assured to get the Rinnegan" which its possible but not guaranteed.
The Rinnegan was mentioned as one of the 3 great doujutsus along with Byakugan and Sharingan, it has been established many times as its own doujutsu.
Is as if there was a way you could go from Byakugan to EMS and people began saying EMS is just another stage of Byakugan.
It has been heavily implied that you need Senju DNA to get Rinnegan. Now again it is possible to go from EMS to Rinnegan but we know nothing on the method of how this is done.
The Rinnegan was mentioned as one of the 3 great doujutsus along with Byakugan and Sharingan, it has been established many times as its own doujutsu.
Is as if there was a way you could go from Byakugan to EMS and people began saying EMS is just another stage of Byakugan.
It has been heavily implied that you need Senju DNA to get Rinnegan. Now again it is possible to go from EMS to Rinnegan but we know nothing on the method of how this is done.