For the us; it would end the US economy overnight. There isn’t a product manufactured in the US or service done in the US that does not involve something from china. Even at ridiculously high tariff prices there’s simply no alternative infrastructure for replacing those imports. Even the trump regime are slaves to capital given that’s the only thing backing the legitimacy of the US.

For china; the only thing imported from the US are luxury/private sector items. It genuinely does not affect the core industries (60% of Chinas gdp is in the public sector) of china, and with China’s welfare system, private industries can fail without the employees ever becoming homeless or starving. There simply isn’t a reason to go that far and needlessly escalate.

Tl;Dr nothing the US can do economically can realistically hurt china, just small parts of its private sector. China, however could cripple the US since the US allowed its companies to offload so much core industrial work to china. None of the actual adults in the US will allow trump to piss off china to the point of cutting off trade entirely, and china isn’t petty.