CentOS 8 support is here in version 92 of the cPanel software.
To install cPanel version 92, you must select a tier it is available in. You can check which tiers version 92 is available by visiting our Releases site.
At this time, version 92 is available in the "Release" tier and will be installed by default on new systems.
Simply install as normal.
cPanel & WHM for CentOS 8 (cPanel Docs)