China absolutely has the power over the US to make the US feel pain. The problem is any use of that power would make China feel just as much pain. It would be self-immolation. The three main things China can do are.
Cut all exports. Ironically, Trump did that to himself so that's why Trump capitulated.
Sell all US assets. Not just bonds. Of course this would absolutely destroy China's economy, so a no go.
Nuclear war. But this is the end of humanity, so also a no go.
So China has the power, but would need to basically be willing to end life as we know it, or do what Trump did to himself. Again, ironically that was the one thing that didn't involve total annihilation and Trump willingly committed seppuku. So weird.
This is the problems with western thinking. Everything has to do with the west. Everything China does apparently is because of the west, or in this case USA. This has nothing to do with the west or USA. It also doesn't really have all that much to do with humanity either. As many have noted, China cares about China. Since they care about China, it's in their best interest to fund something like the WHO in order to prevent diseases spreading as that can obviously effect China. Diseases don't care about borders.
It's the same reason China cares about green tech. Sure it helps humanity, but it's mostly to save China for the future Chinese. If the side effect is the world gets cleaner, all the better. Of course the west twists it as China is developing green tech to have a monopoly on green tech. Hey, if you can do better, do it. Otherwise you're literally burning down the world because China does it better.