Install If You Use Always On Display
If you use your Galaxy S9's Always On Display function, you might want to download the Android Pie beta. It comes with some useful upgrades.
Right now, you can either have AOD turned on all the time or schedule set times. That's not the case in Android Pie.
Samsung's Android Pie update brings a "Tap to Show" function to AOD. This makes it even easier to wake the device up.
When "Tap to Show" is active, you can simply double tap the display to bring up all of your information (time, date, battery life, etc). The information from AOD will be displayed for 30 seconds giving you on-demand access.
Samsung's also added new clock styles including one that shows your calendar with your schedule as well as charging information. The charging info will let you know how much time is remaining until the device is fully charged.