Not easily. you would have to involve expressions or scripts. Chances are, though, that you might get by using pre-composing and actually scaling up the toy mouth to fit your points, do the animation, then scale it back in yet another nested comp. if you enable continuously rasterization, AE will concatenate the operations and it should be more or less result in a loslees scaling operation. The otehr, simpler way would obviously be to scale your footage in a pre-comp, then apply the trackers to the pre-comp and use them directly that way... whatever works best for you.
You are going to have to tell us more about your project. How did you track? Track Points don't have size, they are points. I'm just guessing here that you need to tie four points on the tracked mouth with 4 points on the toy. I'd attach each of the track points to a null named for each area of the mouth. IOW, left corner, upper lip, right corner, lower lip. I'd then attach all of these track points to a null by parenting them. Let's call that null mouthController. Then I'd position the mouth controller and scale the mouth controller to fit the toy. Now I'd attach the appropriate corners to whatever you are using to adjust the mouth of the toy. There are lots of options here so you'll have to give us more specific information before I can give you a concrete suggestion.
Come to think of it you might want to take a look at this brilant system my friend Mathias Möhl came up with. You can get it at AE Scripts. It's called Auto Lip Sync and it's truly amazing.