Recover Photos in the Recycle Bin
If you couldn't tell yet, there are several extremely neat or cool things the Galaxy S9 can do. This next one is more of a helpful feature than a "cool" one. That said, you'll absolutely love it when the situation arises.
With the Galaxy S9 One UI Android Pie update, Samsung added a recycle bin to the camera gallery. That means when you throw away or trash photos, they're temporarily saved to a recycle bin. I can't remember how many times I've deleted something then WISHED I could get it back.
If you didn't enable the trash/recycle bin when the feature arrived in Pie, just open the camera and go to settings. This'll save you in a pinch, one day, trust me. Previously Samsung had a "cloud trash" option, but this temporarily saves photos on your phone in case of emergencies.
It's one more cool thing Samsung thought of to make life's easier for owners.