If the transaction was made from Bitcoin Core, you can use "replace by fee" to send a proper fee to unstuck it. I've never needed to do that. There's also the option of running -zapwallettxes (put -zapwallettxes in front of the bitcoin executable path in a direct access if you are using windows, which I hope you arent) then this would drop the tx and give your money back.
His transaction is not Opt-in RBF, so I believe a simple RBF cannot be done
-zapwallettxes only removes/drops unconfirmed tx in his mempool
and once it's broadcasted to other nodes, he can only wait for it to get confirmed or dropped
but the chance for it to get dropped completely is slim to none, my stuck txs still out there unconfirmed for 1 month now
Also in regards to the network exentually dropping this due to the low tx fees will this be refunded to my wallet or would the coins be gone forever?
gone forever... nope, soon or later it will either get confirmed or dropped (return to its state of unspent)
you can attempt double spent with higher tx fee or do CPFP method to speed it up
if 39ETDdxZ is your own address, you can do CPFP yourself otherwise the owner that address may do it
