4K content

The Xbox One will only output at 1080p

The Xbox One S features 4K Ultra HD Blu-ray, 4K video streaming and High Dynamic Range (HDR) for games and video. In addition to supporting 4K video content when used in conjunction with a 4K TV, Xbox One S will also upscale non-4K content
to display at 4K when paired with a 4K TV. When you set your console resolution to 4K UHD, everything on the console — Home, games, and apps—will display at 4K. 4K content is displayed in its native 4K resolution, and other content (like 1080p content) is
upscaled to 4K.

The Xbox One X - 4K content is displayed in its native 4K resolution, and other content (like games encoded for 1080p) is upscaled to 4K

More info:

https://support.xbox.com/en-US/xbox-one/console/4k-on-xbox-one

Your information is not correct. Actually when you set the xbox one S console resolution to 4K UHD, everything on the console—Home, games, and apps—will display at 4K. 4K content is displayed in its native 4K resolution, and other content (like 1080p content)
is upscaled to 4K.

For more info:
support.xbox.com/.../4k-on-xbox-one-s

Hi there,

let me try to answer your questions.

1 and 2. Yes it can play 4K Blu-ray discs and Yes when set to 4K output it will upscale the content. See this snippet from the support page: "When you set your console resolution to 4K UHD, everything on the console—Home, games, and apps—will display at
4K. 4K content is displayed in its native 4K resolution, and other content (like 1080p content) is upscaled to 4K."

This is the link to the support page with the information:
support.xbox.com/.../4k-on-xbox-one-s

This might help:
https://support.xbox.com/en-US/games/game-setup/download-4k-game-content

This does not help. The "Download 4K game content" option only appears on non-4K Xbox's. This option is not available on the Xbox One X. In "theory," 4K content is downloaded to the Xbox One X by default. This in NOT the case
for my Xbox One X, however, as it does not download the 4K content for Quantum Break. All of my other 4K enhanced games work without a problem. Quantum Break is the only title that I have that refuses to grant me access to Xbox Enhanced content.

Nope, it will honor your set resolution.

From https://support.xbox.com/en-US/xbox-one/console/adjust-display-settings

Allow 4K

This setting allows you to pass native 4K content to your display when available in your games and apps.

You don't have to set your console resolution to 4K to play 4K content. You can set your console to another resolution, such as 1080p, and when a game or app requires 4K (and your TV supports the 4K mode
it wants), it'll automatically switch to 4K. This is good if you want to play 1080p content in its native resolution, but also take advantage of the 4K resolution when playing 4K content.

It will only switch when the Game or App "Requires" 4K