Maybe create a new thread with this question so it isn't off topic.
Anyhow, you will still be able to use the cPanel and WHM on your current machine. Just, without anymore cPanel updates. Eventually you should change your OS. The normal path would be to go to CentOS 8, but that is also EOL. As you are not in a shared environment, Cloudlinux won't really be needed.
AlmaLinux is basically the successor to CentOS and would be the option to go to.
I don't think you need to do it in a rush though. As the notice says, support ends in June 2024. So you got a year and a half to prepare.