BrightenMe

The app brightens the screen to 100%. This is very handy if the screen has a low brightness, and you are in a sunny outside place.
A sunny environment causes a very dark screen, and hence apps and widgets are almost invisible. Without going to a shadow place you would like to brighten the screen as fast as possible. Here comes BrightenMe.
Activating the app makes the screen brightness 100%. There is no need to firstly press a button, unlike other similar apps.
Copy the app's icon to a place where you can find a blindly, e.g. at the top left of right of your main screen.
Preferrably, assign the Bixby button of a Galaxy smartphone to this app.

A few settings have been added:
– The level of brightness is 100% bij default, and can be set to any value between 9% and 100%.
– The executed app can be hidden automatically after a delay of a configurable number of seconds, default is 3 seconds. The user must tick a checkbox to activate this option. Between appearance of the app and disappearance the Settings Icon can be hit to change settings. A delay of 0 seconds makes hitting the Settings Icon impossible. Activating the app again within 3 seconds will prevent disappearance in order to enable changing settings. As an alternative the apps data can be cleared via the system app Settings / Apps / BrightenMe / Storage / Clear data : default settings are then restored.

N.B. After installing the app you only need to grant permission once to change system settings, i.c. for the brightness.