iPad Pro camera settings aspect ratio pics - photo vs square

iPad Pro has 2 camera modes that is the only way I can find to change aspect ratio of the pictures. I assumed square was 4:3 and photo was 16:9 however when editing pics and changing the aspect ratio it’s apparent that these ratios are not correct.

Does anyone know what the aspect ratios are of photos and Square in iPad Pro camera? I can’t find the answer on Google.