Mpv is great with subtitles. Not just being able to switch through subtitle tracks and configure positioning, but also being able to automatically find and play external subtitle files when playing a video. I wrote an article about this: https://www.baeldung.com/linux/mpv-subtitles-automatic. Only issue I found is the documentation for what subtitle formats are supported is lacking. You have to look through ffmpeg code to actually find what formats are actuallly supported.

Additionally, https://subdl.com/ with https://github.com/alexanderwink/subdl is a great resource for finding and downloading subtitles from the comand line.