https://www.gamespot.com/articles/new-fortnite-patch-out-today-adds-xbox-one-x-suppo/1100-6455243/

Epic has announced a new update for Fortnite, which will coincide with the end of the Fortnitemares Halloween event today, November 29. The 1.9.1 patch introduces new content for both the game's Save the World and free-to-play Battle Royale modes, as well as Xbox One X support.

Following today's update, Fortnite will run in 4K on Xbox One X. However, it's unclear if this will be native 4K, nor is it clear if the game will receive any other performance boosts when played on Microsoft's new console.