If it says in the item description, „heat-resistant up to xx degrees“, what this means is often the temperature that will positively melt the fiber!
The safe temperature for wigs made of kanekalon (a common wig fiber) is 70–85°C / 160–185°F. Heat-resistant fibers will take more heat, but you should always test the temperature on a strand first. If it says in the item description, „heat-resistant up to xx degrees“, what this means is often the temperature that will positively melt the fiber! It can take irreversible damage long before that.