[cmsj]

There's no "if", notarization has already happened. As of a few months ago, macOS Catalina warns users if an app hasn't been notarized.

It's the latest step in a multi-year effort to make macOS a little less of a wild-west of software, but as with all the previous steps, it's pretty trivial for knowledgeable users to override - you just right click on an app and choose "Open" and you can bypass the signature/notarization checks.