There should be a very clear and obvious tag for this. Yes, we can search for that information, but in doing so, we can also accidentally find spoilers for a movie we would otherwise want to watch. The info could be crowd-sourced, but should be separate from the normal tags. "Ends a TV Series" or "Part 2 of a Movie Series" would be good. I'm sure there are better ways of implementing, but I feel like this is kind of a necesseity, with everything being a sequel, a reboot, or a sequel to a reboot or a reboot of a sequel or a reboot of a rebooted sequel.

Come to mention it, reboot tags would be good, too. Maybe have the tags be "Sequel of - (movie link)" or "Reboot of - (movie link)"