And, of course, vice versa will also be there, so if you right-click on certain small tiles, you’ll see an option to make it larger. Not all small tiles can be made larger though. Also, the sizes are fixed, you can drag the corners of a tile and adjust it’s size manually. This may change in the future, but that’s the way it is now.
Also, you currently can’t change the color of individual tiles on the start screen. Changing the tile color in Windows 8 is a feature that I’m really hoping comes out with the final release. Everyone loves to customize their PCs and this will be no different.
"Computer Tips: Change Tile Size in Windows 8"
Reference : online-tech-tips.com