`We’ve all known that Xbox One X will feature 4K ever since they announced at E3 but Halo was not there.
source : Irishexaminer.com
As a fast paced shooter, it was possible that 4K would be omitted from Halo to ensure the ideal frame rate of 60 frames per second is retained.
However, a recent announcement by 343 Industries, the game’s developer has confirmed that Halo 5 will receive an update enabling 4K on the Xbox One X.
On the Xbox One, the game used dynamic resolution scaling – dropping the video quality to keep frame rates high.
It is very possible this technology will be used again on the Xbox One X, meaning Halo 5 will only be truly 4K at times when the console isn’t overly taxed by hard to render things such as rapid movement and particle effects.