The upcoming release of tvOS 18.2 will make Apple TV 4K compatible with additional projector and monitor aspect ratios.

In June, Apple promised to add 21:9 support to Apple TV 4K as part of a tvOS 18 update.

Support will arrive with tvOS 18.2, expected in early December, but it will go way beyond 21:9. Native support for the following aspect ratios have appeared in the first tvOS 18.2 beta (via Sigmund Judge):
Automatic
16:9
21:9
2.37:1
2.39:1
2.40:1
DCI 4K
32:9


 The new aspect ratio options in tvOS 18.2. Photo: Sigmund Judge

Automatically or manually
As shown, you can set Apple TV 4K to automatically detect your device’s aspect ratio, which can be communicated over HDMI, although this will not always work.

Alternatively, for example if you use an anamorphic lens, you can manually select the aspect ratio.

There is support for up to 32:9 ultra-wide, which is gaining traction in ultra-wide monitors. The 2.39:1 aspect ratio is typically associated with movie theatre projectors.

Wide and ultra-wide screen support is by the way also included in the visionOS 2.2 beta for Apple Vision Pro.

Additionally, tvOS 18.2 is expected to add new screensavers, including Snoopy and Apple Originals screensavers. These require an Apple TV 4K (2nd Gen) or later.

- Source: X