FFXV was the previous fastest selling FF game. It did:
5 million launch shipment
6 million shipped and sold after 1.5 months (holiday season)
7 million shipped and sold after 1 year
FF7R on one platform will outsell it. It also has already broken digital records for SE: 2 million digital on PSN alone.
I expect FF16 and FF7R2 to be timed exclusive to PS5 considering SE can break records with the Playstation userbase by itself.