When using video preview thumbnails and chapter thumbnails

If I enable does it take a lot of space? Is there a way to put it in another hard drive if going to be big files?

note i know its relative to big so lets say around 2000+ movies

Yes, if you enable video preview thumbnails and chapter thumbnails you will eat up quite a bit of space, depending of course on the size of your video collection. You can move the Plex server data directory to any local drive attached to the computer very easily.

https://support.plex.tv/hc/en-us/articles/202529153-Why-is-my-Plex-Media-Server-directory-so-large-