Short answer: no.
Long answer: Yes, but also no. Kinda. Anything less than serious work will turn a fixed-stock rifle into a rifle with a folding stock. Type81 or not. What matters here is what amount of effort (/money) you're willing to sink into such project. Finding someone with a foldyboi willing to trade 1:1 for your fixed-stock Type81 would probably be the cheapest option. Literally costs nothing more than shipping (assuming you don't get shafted in the process somehow). Home-bubba is the route that perhaps comes with the highest of reward, the feeling of a job well done, but then again not everyone has the skills/time/tooling to see this through. Something to be aware of, the receiver is different between the fixed and folding-stock versions. You can't really swap one for the other. Even if you somehow found a Type81 folding stock alone (or sourced the stock from another Chinese gun out there), you wouldn't be able to just remove one and put on the other.