How to install SSL in RHEL 8

What is it you're trying to achieve? The packages to for SSL for PHP are probably available as standard RHEL rpms available through dnf. If you've got those installed and now need to know how to create an SSL certificate, there are two options available to you. If you do not need to have global access, you can google how to generate a "self signed certificate". These are fine for internal development, and/or internal services that only you or your company is going to use - you should be able to add security exceptions in your browser to accept the cert, even though it does not come from a recognized authority (e.g. Twate). If you do need to be accessible from the Web, then you need to get a cert from a recognized authority. You'll probably want to research Certificate Authorities, what the annual cost is, etc. Each authority will probably have a submission form for you to fill out to get your Cert.