Edited response:
As the article states 90 FPS was enabled today, Oct 13th. I am discussing with the team on why this is not displaying and will get back to everyone ASAP.
This thread was added on October 13, 2020, with posts from FreightTrainUSA.
Original Post
https://news.samsung.com/us/samsung-fortnite-unlocks-90-frames-per-second-galaxy-tab-s7-fortnite-players/
It has not been enabled. Have someone on your team download the patch and try to enable 90 FPS. It does not work for me, others on this sub, nor any of my friends on the tab s7.
After I made my initial post I went to discuss with the team that this was enabled. I will get back to everyone once I find out the details. Everyone can expect a post from myself/Fortnite Status on this subject soon.