Here is a good Apple TV support page.
Press and hold the Power button to turn on your TV and wake your Apple TV. Press and hold the button again to turn off your TV and put your Apple TV to sleep.
https://support.apple.com/en-us/HT205305
If you are looking for a secondary remote with traditional buttons please check out our Button Remote for Apple TV:
https://function101.com/pages/button-remote-for-apple-tv-home