Bitcoin Core pull request [#25600][1] proposed advertising full-RBF on service bit 26 and connecting to four other full-RBF nodes. This was never merged, but some people use this patch on their nodes nevertheless. Peter Todd [maintains the patch][2], and his [Libre Relay][3] fork also has it, among other changes that relax the mempool policy.

However, enough people have probably enabled mempoolfullrbf that you might already be connected to full-RBF peers, especially if your node accepts incoming connections and thus has a lot of peers.


  [1]: https://github.com/bitcoin/bitcoin/pull/25600
  [2]: https://github.com/petertodd/bitcoin/tree/full-rbf-v26.0
  [3]: https://github.com/petertodd/bitcoin/tree/libre-relay-v26.0