https://www.polygon.com/2018/8/28/17790754/halo-the-master-chief-collection-xbox-one-x-release-date-patch-notes

Halo: The Master Chief Collection developer 343 Industries released the most significant update in the game’s history on Monday, patching the bundle of four games to add features such as Xbox One X support and fix a variety of long-standing issues.

The massive patch — the total size is approximately 73 GB if you want everything (more on that later) — arrived ahead of The Master Chief Collection’s Sept. 1 debut in the Xbox Game Pass library. The fixes and additions contained within came about through a collaboration between 343 Industries and the Halo community, which conducted beta testing over many months to get to this point.