I wish in plex, you can add a tag or something similar to a comment like in iTunes, and then when you make a smart playlist, you can have it find movies that you put a specific comment or note.
as an example, I don’t have all the James Bond movies in a collection or play list, but if I was able to add a comment on all the movies , then make a smart playlist look for the movies. then it would make things easier.
You can make a Smart Playlist based on anything you can filter on. All my marvel movies have the studio “Marvel” . if you make a smart playist based on the studio filter any time you add a movie with that studio it will get auto added to the playlist.
If you don’t want to edit a collection tag or nothing else matches among them all you can use the Label tag. (Labels can be used for restrictions as well)
or do something like add your own Bond genre if you want and filter on that. then add that genre to any other bond films you add in the future