Screen Alive Elite has features to allow your device to keep screen awake always or till a specific duration of inactivity. You can make it smart enough to keep screen on while charging or switch to a lower timeout when the device battery is low.

You can keep the notification on and use the overlay button - a new concept to enforce your device to keep screen on. Keeping the overlay button on your screen can also help you to keep screen on during calls.

A resizable widget is available as well that you can add to your home screen. Additionally, quick settings and notifications are given to keep you updated of the settings. All of this with No-Ads! (We, at Snapcore, value a distraction free experience, hence all of our products, whether free or paid, are ads free - now and forever.)
Note: This app requires your permission to make changes to system settings. To use the overlay button, display over other apps permission is required.