The bazarr tip is great, especially if you use radarr and sonarr. Even without it, Plex will let you search for subtitles and can find decent ones most of the time. I ran into enough cases where tv shows didn’t have subtitles so I made a bazarr docker-compose, pointed it at my movies and tv directories, and have had zero issues since. Automatically grabs it and everything, if you want subtitles on something you just downloaded you can go into the webui and search immediately instead of waiting too