Cinderella (1950) - Technical specifications - IMDb
https://www.imdb.com/title/tt0042332/technical/
Aspect ratio 1.37:1
1.37:1 (Academy ratio).
Only slightly wider than the 4:3 ratio used throughout the silent film era, the Academy Ratio was the standard film ratio in 1932 when “talkies” (aka, films with sound) began.