Apple TV 4K (2nd generation or later) includes eARC, which passes full-resolution audio—including 3D surround sound formats such as Dolby Atmos—from an eARC-supported TV (or any HDMI device connected to it) to your Apple TV.
When you set up HomePod or HomePod mini speakers as the default audio output with Apple TV 4K, you can use them to play audio from a game console or DVD player that’s connected to your TV with an HDMI cable.
Connect one end of an eARC-compatible HDMI cable (sold separately) to the HDMI port on your Apple TV 4K, then connect the other end to the HDMI port labelled eARC on your TV.
Turn on your TV, then make sure its HDMI-CEC setting is enabled.
See the Apple Support article Make sure that HDMI-CEC is on.
Set the HomePod (or HomePod stereo pair) as your default audio output for Apple TV.
In Settings on Apple TV, go to Video and Audio > Audio Output > Audio Return Channel, then select Play Television Audio to turn eARC on.
On your TV, select the HDMI input for the device you want to route audio from (such as a game console or DVD player).
The audio for the selected device is routed through Apple TV to your HomePod speakers.
Note: You may need to check with your TV manufacturer to see if additional settings are required to enable eARC for audio output.
For more information, see the Apple Support article Use HDMI ARC or eARC with your Apple TV 4K (2nd generation or later).