No, they (Managed User) add an ALLOWED piece of content to their Watchlist. Next, they go to their Watchlist to view the content (movie’s) details. In those details there is a “Similar Titles in Free to Watch” and other outside content listing hubs. You can open those items up to see the trailers and full movies.
I do not use the “Content Restictions” in Plex. They are too vague. Instead I personally “Only Allow” content based on custom Labels.