What does "downscale" mean in manual crop?

I've enabled cropping, and downscale. The cropping works great, but I'm not sure about downscaling. Does it mean that the image quality is being downscaled? Or is it supposed to resize the image? Anyhow, what I would like is for the user to upload and crop the image, and then it would be resized to a certain maximum size, respecting the original aspect ratio. Is that possible?

Setting crop to "200x300" will downscale (reduce) image to 200x300 if user cropped original to 400x600. You can increase size of any image (see stretch option: https://uploadcare.com/documentation/cdn/).