According to the apple support ,with the Apple TV Remote in Control Center, you can control your Apple TV or AirPlay 2-compatible smart TV with your iPhone, iPad, or iPod touch.
Add the Apple TV Remote to Control Center
If you have the latest version of iOS or iPadOS, the Apple TV Remote is automatically added to Control Center.
If you have an earlier version of iOS, manually add the Apple TV Remote to Control Center. Go to Settings > Control Center, and tap Add next to Apple TV Remote.
To use the Apple TV Remote with an AirPlay 2-compatible smart TV, add your smart TV to the Home app and assign it to a room.
The Apple TV Remote in Control Center works with Apple TV 4K, Apple TV HD, Apple TV (3rd generation), and AirPlay 2-compatible smart TVs only.
Set up the Apple TV Remote in Control Center
Open Control Center:
On iPhone X or later or iPad with the latest version of iPadOS: Swipe down from the upper-right corner of the screen.
On iPhone 8 or earlier or iOS 11 or earlier: Swipe up from the bottom edge of the screen.
Tap the Apple TV Remote.
Tap your Apple TV or smart TV from the list.
When asked, follow the onscreen instructions to enter a four-digit passcode into your iPhone, iPad, or iPod touch. If you have Apple TV (3rd generation), use your Siri Remote or Apple TV Remote to enter the four-digit passcode into your Apple TV.
The Volume button on your Apple TV Remote in Control Center works only when your Apple TV is set up with a HomePod, soundbar, or other AirPlay 2-compatible speaker. If the Volume button is dimmed, use the volume button on the remote that came with your television.
If you can't set up the Apple TV Remote
Try these steps. After each step, see if you still need help.
Check that your iPhone, iPad, or iPod touch is on the same Wi-Fi network as your Apple TV or AirPlay 2-compatible smart TV. On your iOS or iPadOS device, go to Settings > Wi-Fi. On your Apple TV, go to Settings > Network.
Make sure that your iPhone, iPad, or iPod touch is updated to the latest version of iOS or iPadOS, and your Apple TV is updated to the latest version of tvOS.
Restart your Apple TV or AirPlay 2-compatible smart TV. Also try restarting your iPhone, iPad, or iPod touch.
