Bike fit / correct riding position

Of course not, but there's a bell curve of positions. Most people are probably just fine in the 165-175mm range so there's likely little benefit. Only when you have freaks or specific issues would you be looking at crank length changes. In my case, I have a hip problem and we decided to try shorter cranks and open my hip angle up so I bought shorter cranks to suit my bike and requirements and went back and had more fitting work done. It's very unlikely fitters will carry super short cranks but they might identify the issue and suggest them as an option or work a position with the current cranks. Stems, I would expect most fitters to have a wide range of options.

Some fitters have fit bikes that can adjust crank length, so if that was something that needed to be targeted for some reason they could replicate the position on the fit bike and then adjust crank lengths.