Galaxy S9 got support for night mode shooting like in Galaxy S10
Despite the fact that most manufacturers of Android smartphones use their own shells instead of the stock version of the operating system, this does not prevent them from releasing different assemblies for flagships of different years, thereby increasing the scale of fragmentation. As a result, we see that the device, which was honoured a year ago, today lacks the banalest functions that only the flagship of the current generation has been awarded. Fortunately, Samsung was one of the first to move away from such practices.
Following Android 9, Pie Samsung introduced the June security update of the proprietary One UI shell for the Galaxy S9. In addition to fixing vulnerabilities, it contained at least one functional innovation. They became the support of a dedicated night shooting mode, which was previously only available to owners of the tenth generation Galaxy S line of smartphones.

Night mode for Galaxy S9
The night mode was previously built into the firmware of One UI, however, it was activated only automatically if the smartphone algorithms understood that the shooting was carried out in low light conditions. Now you can turn on night mode manually. To improve the frame, the camera slightly increases the shutter speed, requiring you to hold the smartphone motionless during shooting so that the final photo turns out to be a little lighter.
Unfortunately, the night mode of the Galaxy S9 and S10 cameras is very different from the Night Sight mode, which Google Pixel smartphones can boast of. However, perhaps this is for the better. The fact is that Night Sight does not increase the shutter speed, but uses advanced post-processing algorithms as if highlighting the frame. As a result, the picture is obtained as if it were taken not in low light conditions, but at just beginning twilight.