For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:michals:mingw/openSUSE_Tumbleweed/home:michals:mingw.repo
zypper refresh
zypper install mingw64-expat
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:michals:mingw/16.0/home:michals:mingw.repo
zypper refresh
zypper install mingw64-expat
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:michals:mingw/15.6/home:michals:mingw.repo
zypper refresh
zypper install mingw64-expat