Without seeing the specific examples, I'm going to assume you are referring to the chibi type characters. The short answer is yes, there is a method to change the size of any character.
Go in to that character's main .cns file and look for the following lines:
xscale = 1
yscale = 1
You can adjust those by whatever increments you feel necessary to. Changing both 1's to a 2 would cause them to double in height and width. To increase the original size by 150%, you would change them both to 1.5, etc.
Now the real answer is no because they are going to look so horrible blown up that it's probably only a matter of time before you'll change it back or remove them completely. If you can tolerate the horrible appearance, then more power to you. Good luck!
D-Day