If it is just you and no one else (or the experience of anyone else [accidently] accessing your site does not matter), you can just use a self-signed SSL certificate for your IP, which you can create in one click at ZeroSSL for example with Self-Signed Certificate Generator.
Otherwise, as @cpu has already mentioned, you will need a domain name. You could try obtainning some free one (from Freenom or something similar), but I would recommend just getting some name with a reasonably priced extension. Just don't be fooled by the "cheap" registrations which have rather expensive renewals, so study the actual non-action prices of renewals before you commit to buying a domain name.