Guest Notice

Hello

What do you mean by guest?

A new registered user? A new visitor?

Any visitor that is not logged in.

You can create a message on your template easily, following the instructions here:
https://codex.www.ads-software.com/Function_Reference/is_user_logged_in

I didn’t find any plugin, but there should be somewhere, since it’s really simple to implement.

Hope it helps!

Thanks for the info