Notification bar on Galaxy lets you have quick access to toggle some system setting and brightness adjustment. Customize notification panel on Galaxy Note 8 by doing as follows:
1. Open "Settings" app and go to "Display"
2. Tap "Notification Panel"
3. The first check box is for adjusting screen brightness from notification panel. Mark "Brightness Adjustment" to do so.
4. You can add, remove or change the order of quick setting buttons, by tapping, holding, and dragging each icon.
Click on the screen shot below to see it in real size