How to increase the size of a player model?

What I want to do is make the arms, legs, torso, and head bigger using the "robloxian 2.0" mesh. I made my own model with the sizes I wanted and attempted to have the player model take the form of the model; which removed the model in the workspace and only allowing for the 1st person to enter to take the form. But, the script didn't work for some strange reason, and if there was a way to make the player model bigger that would be 10x easier as they would still be able to use clothing that I've made and whatnot. If I can't increase the size, then I'll just resort to working on changing the player model into the model I made