Alter fields in the TLS handshake

Greetings, everyone!

Is it possible to alter the fields in the TLS connection handshake, such as the SNI (Server Name Indication), in a Firefox Extension?

I am planning to update a legacy plugin that previously operated in Firefox 30, and it possessed this precise functionality.

If modifying the fields in the TLS connection handshake is not attainable, could you suggest any recommended articles pertaining to updating an outdated Firefox extension to the WebExtensions API?

Thank you in advance.

Best regards,