What do you want to use this for? It’s probably better to grow towards a specific size (e.g. with a tween), and then do what you want once that is finished (e.g. with tween.Completed).
To answer your actual question though:
Compare the actual components of the Size, like .Size.X.Offset or .Size.X.Scale.
If you just want to deal with pixels and not scale+offset, you can use .AbsoluteSize.X and .AbsoluteSize.Y instead.
Sorry for the late response, but I’m using it for a gui which size depends on a value, like a stamina bar. I increase the value by 20 and sometimes the gui goes over the max stamina. If staminabar is over > size then it changes its size back to the original.