Several HP Printers and Scanners require a non-free software plugin driver to run on Linux distributions. openSUSE does not come bundled with the non-free plugin.
HP provides an automatic installer for HPLIP (HP Linux Imaging and Printing). The installer is known to work on several Linux distributions including SUSE (13.2, 42.1, 42.2, 42.3, 15.0, 15.1, 15.2). Therefore, it should work on openSUSE.
Download the HPLIP installer and run it as follows:
Follow the on-screen instructions to complete the setup. Once done, connect your HP Printer/Scanner. It will be automatically detected and installer.
The files downloaded for the setup will be available in a folder with the same name as the HPLIP installation script, i.e in this case hplip-3.20.9.