For openSUSE Leap 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:SCNOPS:php81/openSUSE_Leap_15.4/home:SCNOPS:php81.repo
zypper refresh
zypper install php8
For openSUSE Leap 15.3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:SCNOPS:php81/openSUSE_Leap_15.3/home:SCNOPS:php81.repo
zypper refresh
zypper install php8
For SLE 15 SP4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:SCNOPS:php81/SLE_15_SP4/home:SCNOPS:php81.repo
zypper refresh
zypper install php8
For SLE 15 SP3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:SCNOPS:php81/SLE_15_SP3/home:SCNOPS:php81.repo
zypper refresh
zypper install php8