Actually it won't. A movie on a 4k blu ray is around 80gb without additional compression. And Oppenheimer is shot on 70mm which is more like 8k resolution. Still would fit on a micro SD of course
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
Reminds me of that time adult swim showed their new aqua team hunger force movie on tv before hitting the theater, but they minimized it to a tiny tiny corner of the screen while they played their normal broadcast