While there is already a @rel="license" option, I think it would be good to have a @rel="tos" or @rel="terms" to help locate the terms of service page for any website. And a @rel="privacy" for privacy policy.
The key difference here is that @rel="license" is about copyright of the document (see 4.6.6.9 Link type "license") and @rel="tos" would be about the rules for usage of a web site/service/application (things like warranty, jurisdiction, etc).
Example:
<link rel="tos" href="https://docs.github.com/en/github/site-policy/github-terms-of-service">
<link rel="privacy" href="https://docs.github.com/en/github/site-policy/github-privacy-statement">