Use APKPure App
Get Screen Lock old version APK for Android
Screen off without pressing power button (Virtual Power Button) (Only 90 kb).
This app provides a virtual screen lock button to quickly turn off the screen.
This app uses "Device Administrator Permission" which is required to use this app.
To uninstall this application deactivate this app from Privacy Settings >Device Administrators and then uncheck this application after this uninstall will work.