To deny the US the use of any nearby airfields (Okinawa, several others in Japan an Philippines). This will limit US airpower to carriers, which are few and sinkable.
Of course, China wants to be able to fight those F35s in the air - to mitigate the damage they can do to them (while the F35s still have airfield/carriers to land on) - also in order to make it easier to sink those carriers.
Still, you can bet that all US nearby airfields would be peppered very early in the conflict.
There won't be a direct conflict with China, at least not in the last 10 years, because the US first needs to complete de-coupling his economy from China more, re-industralize in-shore or at least near-shore, and dramatically build up its military and logistic capabilities to fight an expeditionary campaign on China shores.
China also is not stupid, and no matter how much they posture, they won't invade Taiwan.
No one is invading China. Coupled or de-coupled is a completely irrelevant consideration. People think MAGA are crazy, but no one is suicidal. A war with China would be over in a matter of hours. And anyone who did not manage to get to Africa or extreme South America before the outbreak of hostilities would have a great chance of dying. The only question is will death be quick in a blast, or slow as you try to walk out of the US.
Why would the opening salvo be ICBMs?