343 Industries have confirmed that Halo 5 will be receiving native 4K support for Xbox One X. The game currently runs at 1080p on Xbox One.
The company stated..
“Today we are excited to officially confirm that Halo 5 will receive a game update to support true 4K with the release of Xbox One X later this year! We’ll have more to share on this front as we get closer to release, so stay tuned.”