Final Fantasy XVI will have two performance modes, according to Square Enix's producer, Naoki Yoshida, who will be there at PAX East. This leaves us with a choice of a 4K resolution graphics mode at 30 frames per second, or a 60 frames per second frame rate mode at a lower resolution (probably 1440p).
Final Fantasy XVI will be released as a timed exclusive on PS5 on June 22nd.