Insomnic_1’s solution is probably the closest the OP is going to get what they want.
However, Plex is one step away from making the OP’s dream come true, if Plex would allow Nested Collections as seen in that feature request. You could then create smart filters for the majority of these actors the OP wants a page for, then create one giant “FAMOUS ACTORS” collection that contains each of these smart collections. Then you can pin this collection to the Home Page, which would display a single pic of each "collection, which you could quick-select to see their movies. For more on this, see the “Add as a Recommendation Row” section of this article for how to pin the collection to your Home.
Of course, you can’t do a collection of collections NOW, but at least you know about making a one-level Smart Collection thanks to Insomnic_1 and now how to pin it to Home.
