I'm looking to create a raw transaction, sign it, and broadcast it using the eth.sendRawTransaction RPC method.

I would like to do this offline using code or an open-source library OR online but without the need of using an specific wallet or software.

There is neither a RPC method to create/sign the raw transaction, nor can I find any libraries to do this (offline).

Any help or guidance on how this could be achieved would be most thanked.