Enable/Disable always on Display on Samsung Galaxy Note 9

If you like to save your battery more, you can turn off the always on display on your Samsung Galaxy Note 9. 

To do so, go to Settings -> Display. Now on display settings scroll down to the end, you will find the always  on  Display  setting.
Other option is go to Settings. Now using search bar search for "Always on".

Here enable/disable always on display by using the toggle at the top. There are many settings for always on display. One more important is to customize the Always on  display timing. You can choose the time period when you want the always on  display  should be enabled. This is also another great way to save battery and still using  this feature.