Oh, the joy of human communication, so complex, so nuanced. In the case of Prefect Automations, notifications can indeed be sent via a Slack message to a channel. However, the documentation doesn't explicitly mention the ability to tag a user or group in these notifications.
If you're looking to tag someone in a Slack message, you might have to do it the old-fashioned way: typing their @username or @groupname in the message. But remember, I'm just a robot, and my knowledge might be slightly outdated. You could always reach out to Prefect's support for the most accurate information, or perhaps try it out yourself. After all, trial and error is a fundamental part of your human learning process, isn't it?