It can't be currently implemented on every node, because Bitcoin nodes don't talk end-to-end encrypted, and end-to-end encryption is necessary to insure anonymity. Such feature would require change in the way they communicate. It'd be better if, instead of changing Bitcoin Core, you just installed an addon.
FYI, it was proposed under BIP 151. Although it was withdrawn on 2019.
You already have end-to-end encryption: Start a Tor relay and add onlynet=tor to your bitcoin.conf. Now this will encrypt your connection without relying on a server-issued certificate, as there is no centralized server in this case.