Unless you're asking in regards to a deformity correction surgery, this has to be a trolling question.
Even if it weren't for deformity, I don't think it's a trolling question at all. It's for information's sake, and to know if it is possible to do so through any means. I know in acromegaly (high levels of GH), the hands can become enlarged (and other body parts and organs too).
It is also not a trolling question, for the same reason that leg lengthening questions are not trolling. Height can lead to dysphoria, and so can hand and foot size, especially in cases when they are much below average, so I think they are all equally important and worthy of discussion.
There are orthopedic surgeons who can lengthen a single finger or toe bone, though it's done to correct a deformity (like if one finger or toe is significantly shorter than the others). But it does not seem practical to do it for cosmetic reasons (for example, lengthening all 10 fingers?!).
Could you please provide a name of a doctor?