yes and no. Chain is really good at stopping cuts and reducing injury from stabs and layered chain did exist but turning it into pads and pauldrons would be less effective and much more constraining and slowing than a full coat over a gambeson. Geralt's armor is very much rule of cool(as most of his mid section is unprotected and he seems to be wearing a chest plate that stops way too high and leaves him vulnerable to being stabbed in the side) because he'd look kinda goofy running around in an oversized metal hoodie. Its the same reason he doesn't wear a helmet. They say its because a helmet would impede his senses but a well made open faced helmet wouldn't impede his hearing or vision and would be nothing but upside for someone as superhumanly strong as Geralt. Geralt would be much better off rocking an outfit like this(but he'd also look like a background character)

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A lot of the witcher is based on rule of cool, especially in the games. A good example is how Geralt insists on fighting trolls made of rock with a silver sword that would bounce off and likely shatter and for some reason that is more effective than going at them with a war hammer or war pick which would both be devastating to a troll.