--add-peer xmrtolujkxnlinre.onion:18081... that is the known onion node for xmr.to
Here is your misunderstanding: --add-peer is for adding peer nodes, nodes that will talk to each other on the Monero P2P network. It is not for using another nodes JSON RPC interface (which is all that xmrtolujkxnlinre.onion is offering up [ref]).
Thus if you want a full ...
You are getting a CORS error:
Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://server.ip.address:38083/json_rpc. (Reason: CORS request did not succeed).
From the help:
How do you setup a node to communicate with other nodes only over an anonymous network?
Pretty much all of this is covered in ANONYMITY_NETWORKS.md.
Node to node communication, i.e. P2P traffic: for this you can use --tx-proxy ... and --add-peer ... / --add-exclusive-node ... with a node on an anonymity network to broadcast transactions only over the ...