You can use Send to securely share a password with someone, but if you want them to be able to collaboratively edit the credential, there is no way to do that with Bitwarden unless you add the user to your organization.
If you are hosted through the Bitwarden cloud, I believe a free user can be added to your organization (you may wish to contact the Bitwarden CS team to confirm). If you are self-hosting your own Bitwarden server, then I think it gets more complicated.
You write “You can use Send to securely share a password with someone”
Where would I find this function?
I only see the option “file” or “text”