Bitcoin Core pull request #25600 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, and his Libre Relay 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.
