In reality there is a nuclear hotline between the two countries. If the US launches a ballistic missile attack, they will notify the Chinese side. In which case the Chinese side simply replies they are also launching a conventional counterstrike. US early warning sensors would then verify that inbound Chinese ballistic tracks are not aimed at the US's strategic deterrent (straightforward because US ICBM silos are located far away from industrial centers).
In reality, since the US is behind in procurement of hypersonic weapons and conventional MRBMs, I dont see the US going for Chinese industrial targets with BMs if conflict occurs within the next 5-10 years. US can try with long range subsonic cruise missiles, but I dont believe such attacks would find much success.
As long as China continues to build up both its strategic and conventional deterrence, I don't forsee the US launching large scale conventional attacks on Chinese urban centers and civilian targets. US timidness in the Ukraine conflict should be informative regarding US appetite for escalation. What China should focus on is defensive countermeasures against hypersonic weapons and antiship BMs. If such systems are developed successfully by the US/Japanese and deployed in sufficient numbers, then the PLAN'S operational freedom within the first 2 IC may be severely limited unless countermeasures are in place.
My view is that China should focus more on offensive capabilities that deny the US use of the Western Pacific.
So China won't face large scale conventional attacks by the US in the first place.