For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:Pantheon:Branch/openSUSE_Tumbleweed/X11:Pantheon:Branch.repo
zypper refresh
zypper install elementary-wallpapers
For openSUSE Leap 15.2 Ports run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:Pantheon:Branch/openSUSE_Leap_15.2_Ports/X11:Pantheon:Branch.repo
zypper refresh
zypper install elementary-wallpapers
For openSUSE Factory run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:Pantheon:Branch/openSUSE_Factory/X11:Pantheon:Branch.repo
zypper refresh
zypper install elementary-wallpapers