There are a few ways that you can find your hotspot password on your Samsung S9.
One way is to go into the settings menu and look for the “Tethering and Mobile Hotspot” option. Once you select that option, you should see your password listed under the “AP Settings” section.
Another way to find your hotspot password is to use a third-party app like WiFi Key Recovery. This app will allow you to view all of the passwords that are stored on your device, including your hotspot password.