-snip- For addresses that have an output transaction, people retrieve R, S and Z values from a Bitcoin Transaction. The process of obtaining (extracting) R, S and Z values from a Bitcoin Transaction is known and understandable to me. Another thing is not clear - the practical application of the parameters R, S and Z. Is there a thread on this forum that discusses the practical application of these parameters R, S and Z?
This is the general principle of digital signatures. Having the private key the owner can sign any message (as well as the outgoing transaction). Signature of the message is a point. After that anybody can verify this signature with the public key.
And secondly, the 2coin.org resource often freezes and does not work. Is there any other resource similar to 2coin.org? Perhaps there is a stand-alone script or software option on GitHub? Tell me.
What is your main goal? If you just need to take r, s values from raw transaction - you can easily do it. The structure of the transaction is described in the links provided earlier by me. If you want to understand how these values are calcualted - the description is also in the links above.