In filestack v2 I was able to force users to crop an image after they uploaded it using the 'cropForce' attribute like this:
filepicker.pick(
{
mimetype: 'image/*',
cropForce: true,
cropRatio: 8/2.5,
conversions: ['crop'],
services: ['CONVERT','COMPUTER','INSTAGRAM','URL','FACEBOOK','GOOGLE_DRIVE','IMAGE_SEARCH']
}, function(response){
}
);
However in filestack V3 there is no more option to do this?