There's no built-in way to do this as far as I know. Bitmaps are stored for all the different sizes of text that you need based on font sizes used in your project so those are the only ones you have immediate access to.
You could probably build a buffer with the largest size that your desired text will be and then scale that buffer to different sizes to display on your screen in sequence. This would all be custom and fairly involved. If you have a predefined static image (or a set of them to choose from) that you can use for the zoom sequence it would be easier.
