Some game systems let you take various abilities and skills, balanced against various flaws or disadvantages. Often these elements relate mainly to ability - what you can or cannot do. But sometimes they refer to actual physical differences in your body (which in turn affects what you can or cannot do as a side effect).
So yes, in some games you can take differently sized limbs or body parts with unusual strength... or other unusual aspects. Presumably if you take a big liver, you'll be really good at digesting fatty foods and alcohol. Which could come in handy, given the typical diets of many adventurers!
C-3PO: Hey, everyone!
Leia: Sally! How'd the protest go?
C-3PO: Great! Ben, thanks so much for dressing up as Dr Zaius.
Chewbacca: Never. Again.
C-3PO: And thanks so much, Jim, for suggesting it.
Han: My pleasure!
C-3PO: Those monkeys really need our help.
Luke: If they were anything like the oppressed robots in your campaign, they'd just break out and run amok through the place.
GM: That was fun though.
R2-D2: Yeah, but we were the robots.
Luke: The chimps don't get to min-max their arms for bite strength though.
C-3PO: No, they took large brains.
Han: Wait... You can do that?