The latter is the existing behavior, while the first one will let you truly remove something that was sent to another contact/everyone. That said, Google does note how “Messages may still be seen by ...

Google Messages for Android will soon let users delete a chat message for everyone in an RCS group conversation. This means that users can now remove a message from a group chat so that it disappears ...

Not that long ago, sending a message was final. It didn't matter if you had an embarrassing typo, or you sent a message to the wrong person: Once you tapped that "send" button, you were locked in, and ...