Well, I really don't have much experience with patent leather, but generally, it's not considered stretchable because it is, by definition, a poly that's bonded to a leather substrate. However, if it's just a matter of loosening up a toe box a bit, then I'd say a trip to the cobbler might be worth a try. But keep in mind that this is definitely one for the professionals and
not for the at home do-it-yourselfer. A competent cobbler will try some sort of solvent to loosen up the leather a bit and then try to, ever so slowly, stretch the shoes. He may need a week or so, as the stretching force will have to be applied very slowly. This is one job that, if it's to be tried at all, must not be rushed.
For my money, unless you're talking a very minor stretch, I'd sell or trade the shoes and buy something else.