You probably don't need one, but it's nice to have the option

Let's Encrypt, a certificate authority (CA) known for its free TLS/SSL certificates, has begun issuing digital certificates for IP addresses.

It's not the first CA to do so. PositiveSSL, Sectigo, and GeoTrust all offer TLS/SSL certificates for use with IP addresses, at prices ranging from $40 to $90 or so annually. But Let's Encrypt does so at no cost.

For those with a static IP address who want to host a website, an IP address certificate provides a way to offer visitors a secure connection with that numeric identifier while avoiding the nominal expense of a domain name.

...read more at theregister.com