How to Whitelist one user to a specific site?

I owuld like to be able to whitelist a particular userID to a wedsite (or URL).

I have been just whitelisting sites (URL or recipient sites) or just whitelisting Sender, BUT I would like to whilelist a combination (user-to-site/url). This could give me more granular control for some specific user.

Can someone advise on the best way to accomplish this, in version 12.5

Thank you.