XF 1.5 Restrict forum content, but not navigation


I'm active on a xenforo forum (not mine) that is fully navigable by the public (non members) but not accessible. Hovering over the threads doesn't show the summary and clicking on them triggers a sign up now pop up. Of course if you are logged in with a valid membership, everything works as usual.

Is this a setting that can be adjusted in the default xenforo build? Or is this custom built? I would like to do something similar.

It is the rivals forum that I'm referencing in my example. You can see it at work here: https://texas.forums.rivals.com/forums/inside-the-40-acres.22/