bavard
I just stumbled over a recent discussion: Allow to start discussion in certain tag only for one user group and here especially a post by clarkwinkelmann
I think @jordanjay29 suggestion was to set admin+mod under "global", and members under the newbie tag.
I have just tested locally and it seems to work.
At first I couldn't believe it because it contradicted my previous explanation that tags were only able to further restrict the allowed audience and not expand it. But that's not what Clark said. He said:
clarkwinkelmann If a discussion has a single tag that the user can't see, it won't be visible.
Obviously, "global" does not act like a tag. I have always thought that "global" is a kind of invisible and non-removable default tag applied to all discussions. We can still see it that way, with the one exception that "global" restrictions can not only be tightened but also relaxed by tags.
This looks like good news for you: You can restrict "global" to regular members and setup a special tag for new members. Simple as that.