While it is possible to modify the existing “1.33:1” entry to “1.37:1” on the Windows platform, it is not possible on the iOS platform.

Given that the vast majority of all sound films prior to the late 1950s were released in “1.37:1” (“Academy Ratio”), and NOT in “1.33:1”, it really should be one of the choices on the pick list. While it sounds like a trivial difference between the two ARs, it is not. The 1.33:1 is a full aperture frame on 35mm film, while 1.37:1 is reduced and offset on 35mm in order to accommodate a soundtrack. There is less detailed visual information in a 1.37:1 frame.

https://en.wikipedia.org/wiki/Academy_ratio