Actually, we can change the size of a character, but it's not possible to do it during an animation.
Very frustrating and limited for fantasy projects including magics, transformations, giant monster, power effects, ...etc.
This is an essential feature and I'm sure I'm not the only one who need it!
I already made a ticket with iClone 7 about it three years ago. This feature is available in all animation software, but I don't want to change just for that...! There is no way to just "unlock" the scale tool? I wonder why it's possible to use the scale tool on objects but not on characters.

For the moment ,the only way to do that is :

-to change the size of the environnement/objects to give the illusion that's the character which is changing size if the camera is correcly positionned. (but can work only if there is one character in the scene.)

-The second tricks would be to make the animation of a character in iClone, then export the character with the animation, then import the character you just exported. It won't be anymore a CC3+ character, but at least you can make the changing scale effect animation. It's a lot of waste of time as you need to put the character at the same position of the old one which you have to "hide visibility", and then reimport a new CC3+ character with the new size at the good location.

I could earn many hours of work and stop to use tricks if that feature would be available. So please, I would love a better solution : Unlock the scale tool for characters!