@mmja I modified your feature request title to remove a superfluous and potentially misleading claim (old title: “Add 3x protection to Bitwarden database instead of current 1x protection”; new title: “Add 3x protection to Bitwarden database”).
To contribute to the Bitwarden code base, start here.
In addition, before doing anything else, I would strongly recommend that you familiarize yourself with Bitwarden’s security architecture, by studying the following materials:
Finally, you should know that Bitwarden has no plans to implement anything equivalent to 1Password’s “Secret Key” (which is what you seem to be referring to with your “securitytoken1” suggestion), as explained here.
Also, Bitwarden clients are expected to support off-line use, but you already know that.