That depend. Russia knows that Ukraine park their jet fighters in NATO territory, but they never struck it. Will China be different? Hmm... Who know. It depend on how far China willing to take the risk. Will they take the risk to take all US, Japan, Australia, NATO, etc in one go, or just stay with Taiwan, but to risk getting bombed by Taiwan F-16V who park in Okinawa and Philippine. Russia don't have the gut to do that, Do China have? That's the question.
I'm sure that US and their allies will use the same strategy as what they do with Ukraine. They won't join the war directly, but will use everything their might to sabotage China, like what they do with Russia. So, will China all in, and start the world war 3 or just take the Russia suffer like now. I don't know.