Although these will "work" today in popular browsers and with most tools, this is NOT the right way to scribble a DNS name into a certificate this century.

Write SANs. Subject Alternative Names. These aren't aliases, the "alternative" means in the sense that this is an "alternative" to writing human readable X.500 series Common Names. Unlike those human names, SANs are defined in a machine readable way, e.g. the dnsNAme SAN spells exactly DNS A-labels, the ipAddress SAN is just an IPv4 or IPv6 address written out as raw bytes, not a dotted decimal or whatever else someone thought might be fun today.

You should also write one of the SANs you choose as the Common Name in some plausible text format, but by having SANs all vaguely modern tools can just match those rather than trying to make sense of the Common Name.

In a very new OpenSSL you can actually do this from the command line sort-of sensibly. In most installs you will need to modify that configuration file instead, you're already using a configuration file so that's no big deal.