Hi @pcrightler,
Warm greetings from the Roku Community!
We will be more than happy to assist you with your inquiry. Please be advised that it cannot directly control other devices connected to your TV, such as an audio/video receiver (AVR) or soundbar. However, your TV may be able to issue volume commands to your AVR or soundbar using a technology called HDMI-CEC.
You can also check out this support article here.
If you need anything else, please let us know.
All the best,
John
John
Roku Community Moderator