Bitcoin Core pull request #25600 proposed advertising a full RBF on service bit 26 and connecting it to four other full RBF nodes. This was never merged, but some people use this patch on their nodes nonetheless. Peter Todd maintains the patch and his Libre Relay fork also has one. Additionally, there are changes to relax the mempool policy.
However, enough people may have mempoolfullrbf enabled so that they are already connected to a full RBF peer. This is especially true if the node has many peers, accepting incoming connections.