It is seems like at the moment it is not possible to set the collision mask bigger than the base image.
Not sure if there is any technical reason for this limit but it would be nice and useful if we could set the size of a collision mask as big as we want it to be.
The problem I am facing right now is that I have a bunch of sprites that meant to be clicked or touched in game but especially on a small screen with big fingers, it is difficult to touch them. So the solution I was thinking I can just increase the collision mask, but no, I can not because the collision mask can not be bigger than the actual image.
Some might say, no problem just load the images in to an image editor and add some more empty space. But consider that we are in a production environment where time is money and we have 100s of images to go through.
If we could set the collision mask to be as big as we want it to be and share the same collision mask between all animations of the sprite, we could reduce the amount of time required to get this working significantly.