aspect
Aspect ratio of the generated images. Supported values are "1:1", "2:3", "3:2", "3:4", "4:3", "9:16", "16:9", and "21:9".
Aspect ratio of the generated images. Supported values are "1:1", "2:3", "3:2", "3:4", "4:3", "9:16", "16:9", and "21:9".