- Select TV providers have created their own IR remote to work with Apple TV (e.g. Spectrum, Salt).
- Select independent sellers have IR remotes of their own design to work with Apple TV. No official status though. Search Amazon.
- Universal remotes can be used with Apple TV, if you prefer that. Use other remotes to control Apple TV - Apple Support
Volume controls should work out-of-the-box for most audio setups. The volume control signals are aimed directly at the TV or audio system (not through the Apple TV box, with a few exceptions). For setups that require non-standard signals, users can learn the remote a new device.
Settings﹥Remotes and Devices﹥Volume Control﹥.
If Auto doesn’t work, then try a manual setting (e.g. TV via IR).
If your Apple TV remote isn't working - Apple Support
Try to restart just the remote (TV + Volume Down buttons) for a fresh attempt at full functionality.
Also see: Control your TV or receiver with your Apple TV Remote - Apple Support
right now, every function works except the volume
What is your audio setup? Do you use a TV’s built-in speakers, or something else?
The Apple TV user guide has 12 pages on using the Siri Remote. Try reading that for additional information on intended use, including swipe gestures with the thumb.
Use the Remote - Apple TV user guide - Apple Support (+ open Table of Contents)