A Soft-Key to set the device to standby by use of min. authorisations.
By use of this app a soft-key is available which switch-off the display and set the device to standby.
All ad-free and with a minimum of required authorisations.
Before uninstall the app, the device adminitration authorisation has to be disabled on:
"Settings->Lock screen and security->Other security sttings->Device administrators"