This adds a new quick settings tile that, when toggled on, will set your phone's screen timeout to 10 minutes. When clicked again, it restores the timeout to whatever it was before (usually 30 seconds). In practice this will effectively keep your screen on and at normal brightness so you can read news, social media, etc. without the screen turning off prematurely.

When you run it the first time, it will bring up a system dialog asking you to assign permission for the app to modify your system settings. Click the slider so the permission is enabled, then press the back button.

Next you have to add the new quick settings tile to your quick settings panel. This process varies based on your phone model.