I use the Dropbox Smart Sync feature a lot. It shows your complete Dropbox folder content, but files set as “Online only” are only synced to your computer when used.
I tried this as well with movie folders, which I added to my Plex Server. Because Plex scans and “touches” my files, Dropbox starts downloading them. That is not the idea…
Will there be Plex Server support for Dropbox Smart Sync folders on macOS?