Pre grow on blur top

This is hopefully a simple one, is it possible to get a “pre grow” option on the blur top, similar to the pre shrink, that scales any content out before blurring it.

The use case is for using meshes to create masks, I’d like the blur to start on the edge of the surface, if I render a white surface, then use the pre grow to make the mask larger before adding blur to it.

Possible?