If such an option existed, I'm guessing there would need to be other options too, no?
For example, how would the application be expected to handle things if the new canvas size is smaller? Should it crop the image? If so, how? Crop all four sides? Just two? Perhaps rescale the image to be smaller?
If the new canvas is larger, should the image be stretched to fit? Or should it remain as is with the canvas color surrounding it?