The first reviews of the Apple TV 4K are out and it appears that Apple is working on adding support for Dolby Atmos in a future update for tvOS, according to The Verge.
Atmos coming later
Nilay Patel has reviewed Apple TV 4K for The Verge and has included an interesting detail about Dolby Atmos support. Apple TV 4K and tvOS does not currently support the object-based Dolby Atmos format.
- “Apple told me that the lack of Atmos isn’t a hardware limitation, and that support is on the roadmap.”

Apple has yet to issue an official statement regarding the matter.
The Verge also found that Apple TV 4K currently upscales and outputs the entire video interface in HDR, meaning your TV will go into HDR mode regardless of whether the source is SD, HD or 4K HDR. The output can be set to different combinations of resolution, HDR format, and frame rate from the settings menu. Full review is available via the source link.
- Source: The Verge