Doesn’t always work on my Sony TV. If you turn the TV off without exiting an app on Apple TV, Apple TV is still on the following morning regardless of any setting. Exit the app and it goes to sleep as per Settings.
"I just tell Alexa "Good Night!" and she says one of many pleasant responses, turns off my TV and Hopper3 or ATV 4K (since the CEC on the TV takes care of the ATV if I have been using it) and then slowly dims the lights to off over 30 seconds . . . .
… after reporting on what you were watching and when, how many and what kind of smart lights you own, what time you said good night, etcetera, etcetera…