No, this is only for players. All other sprites have grid sizes defined by a frame's width and height:
For NPCs you can grab the defaults by doing maths on their original sprites, but you can set the dimensions using "gfxwidth" and "gfxheight" as described in this post:
viewtopic.php?f=35&t=425
As for background objects, you have to use the sizes of the original graphics.
As for blocks, you can freely resize them if you use PGE, but you have to keep animating blocks at their original height.