Sleep Timer lets you fall asleep and it will auto turn music off after amount of time or meet battery condition. Beside you can set to turn off: Wifi Bluetooth Screen.
Sleep Timer is totally Free. Hope that it is useful with you!

Major functions:
• Turn music off
Sleep Timer works with all media players as Youtube Facebook video Spotify...
• Turn Wifi & Bluetooth off
Sleep Timer helps to save your phone battery when you don't neet to use Wifi/Bluetooth
• Turn screen off
Sleep Timer can turn off your screen when the timer runs out or meet battery condition.

NOTE: turn Wi-Fi off only support on device bellow android Q

Permissions Notice
• Internet: for bug reports & get new configuration.
• Wifi / Bluetooth: Allows Sleep Timer to turn off Wifi/Bluetooth.
• FOREGROUND_SERVICE: Allows to start foreground in a service application needs it to show an notification from service.
• Device Administrator permission: Allows Sleep Timer to turn off screen. You can disable it from the Android settings or Sleep Timer settings at any time.

Note - How to uninstall:
If Device Administrator is active you need to be deactivated before uninstall. You can de-active as step:
Open Sleep Timer => Settings => Remove device admin => then you can uninstall normally.
or
Settings => Biometrics & Security => Other security settings => Device admin apps => uncheck Sleep Timer => then you can uninstall normally.