Ahha! I found it, it is only in the manage library settings when adding or editing and only for the plex movie agent.
I am currently transitioning from Kodi and would like to use my existing Kodi nfos and artwork and I believe that if I use TMDB agent, I can set the agent order to be:
XBMCnfoMoviesImporter
Local Media Assets (Movies)
TMDB
Fanart.tv
Plex Movie (legacy)
However, for TMDB agent, there doesn’t appear to be an option to use original titles.
I am reluctant to start again especially when I know that TMDB doesn’t have the correct certification for a lot of my movies, which I have manually corrected in the nfos.
The nfos do have the original title and title the same, however, so if XBMCnfoMoviesImporter is working correctly, in theory, this should solve my problem, no?