Code to access the "Auto" option in the Crop tool?

There's no way for a plugin to access that option via the SDK. However, it can set Transform > Level, which does the same thing as Crop > Auto:

targetPhoto:applyDevelopSettings {
    PerspectiveAspect = 0, 
    PerspectiveHorizontal = 0, 
    PerspectiveRotate = 0, 
    PerspectiveScale = 100, 
    PerspectiveUpright = 3, 
    PerspectiveVertical = 0, 
    PerspectiveX = 0, 
    PerspectiveY = 0}