Depends on the kind of printer you have.
Is your printer Wi-fi/Bluetooth capable?
If it is Wi-Fi capable, please connect it via Wi-Fi and your S9 as well. This should allow the printer to show up on the list of printers that your S9 has access to.
If it is a hard line connection only then you'll need converters to change what your printer connection is until you hit the USB-C connection.
Hopefully this helps!
Open your settings Menu> tap on "Connections"> next tap on "More connection settings"> then tap on "printing"> you will want to make sure the "near by devices" setting is toggled on first if it is not already on> then when you're in the printing tab> you'll need to tap "download plugin" which will take you to the Google play store where you can install the compatible app of the make and model of your printer. From there the app will instruct you on how to connect your S9 to your printer.