We could send a couple of missiles into the Three Gorges Dam and deal a severe blow to the Chinese economy.
Although that would be an economic blow to China, the political fallout from the humanitarian devastation that would result would isolate the U.S. amongst its allies. China also generates most of their power on Coal, so the production harm would be negligible. Cutting off trade due to an embargo would be far more devastating, however since China is the world’s largest producer of rear earth metals and lithium, an embargo would cause significant harm on our economy as well. A better tactic, IMO, would be to sink their navy as quickly as possible, then block them from invading our allies to their west. Isolate them, systematically dismantle their infrastructure and production from the air, then invade. It worked in WWII and Iraq, and that tactic would work in this case, just the scale would be much larger.