For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:LXQt/openSUSE_Tumbleweed/X11:LXQt.repo
zypper refresh
zypper install lxqt-powermanagement
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:LXQt/15.6/X11:LXQt.repo
zypper refresh
zypper install lxqt-powermanagement
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:LXQt/15.5/X11:LXQt.repo
zypper refresh
zypper install lxqt-powermanagement