It’s way bigger than that. Usually cinemas receive movies in multiple terabyte hard drives. Thats because they are using JPEG2000 standard (it varies, but it is close to lossless) and a movie can take up anywhere from 500GB to 2TB (highly dependent on resolution, it can go above 2TB). https://en.wikipedia.org/wiki/JPEG_2000?wprov=sfla1
You could use FFMPEG to reencode the audio to a suitable audio levels without touching the video. I am unfamiliar with PLEX player though.
How else do you think they are able to afford servers? Donations? HAH, right…
No, it is our job as humans to create great moments. All we do now is collecting, putting it on the internet and hoping for a dopamine rush from internet points.