Plex has its own metadata backend that’s fed by data from various sources, e.g. IMDb, TMDb and TVDb.
You can provide matching hints, as for what show belongs to, though it doesn’t generally matter if you use the id of TMDb, IMDb or TVDb as hint.
However, you can tell Plex which episode ordering you want to apply to that show — configuring the show to use the episode order from TMDb (aired) or TVDb (aired, DVD, absolute, custom orders). This can be useful if there’s different orders.
TL;DR: you cannot tell Plex to use e.g. descriptions of a specific source at this point.
Putting things on TMDB is important, as it is the primary database for Plex.
Both websites agree on the ordering of the episodes so far, so there is no need to explicitly select one.
/Series <- your series library needs to be pointed to this folder!
/A Remarkable Place To Die (2024)
/Season 01
A Remarkable Place To Die - S01E01.ext
My recommendation would be to always add the (year) to the folder name.