You can try manually morphing a toon figure if it had suitable and sufficient morphs (Your chances of that are better if you're female - there are only a few male toon figures), but otherwise you'd need a modeller or possibly the DForm plugin to make a brand new morph by moving the mesh around or a modeller and Poser to make a complete new figure. You can't really expect an automatic process, I fear  -there's too much judgement in making a caricature.