You have to enter the char .cns file, and seek this: [Size]
xscale = 1 ;Horizontal scaling factor.
yscale = 1 ;Vertical scaling factor.
Change the values for bigger or lower ones (2, 3, .5, .25, etc). If you see some projectiles or animations still are in a big size, seek this line:
proj.doscale = 0 ;Set to 1 to scale projectiles too
And change the value to 1. Hope I helped