Hi,
You should enable the experimental repository.
# percona-release enable pxc-80 experimental
* Enabling the Percona XtraDB Cluster 8.0 repository
<*> All done!
yum list available percona-xtradb-cluster
Loaded plugins: changelog, fastestmirror, ovl
Loading mirror speeds from cached hostfile
* base: d36uatko69830t.cloudfront.net
* epel: mirror.csis.ysu.edu
* extras: d36uatko69830t.cloudfront.net
* updates: d36uatko69830t.cloudfront.net
Available Packages
percona-xtradb-cluster.x86_64 8.0.18-9.1.rc.el7 pxc-80-experimental-x86_64
#