We have these advantages over them and a war with China would mean an instant end to any debt we owe them for $$$ borrowed to fight the Iraq War. However since the 50’s, 60’s and 70’s they have a modern state of the art military plus can enact cyber warfare and attack our economy and financial institutions.
While their military is state of the art by Global standards, it is based on conscripts, has a Soviet command and control system and they do not have the logistical capability of supplying much of that force outside of China. Most of their navy is just a glorified shore patrol and is not Blue Water capable.
Meaning, in short, they could defend themselves from invasion very well, but cannot efficiently project power very far from their own borders, other than throwing nukes around.
Back in 79, China invaded Vietnam to get the Vietnamese to withdraw from Cambodia. After advancing about 30 miles and thousands of deaths, the Chinese declared victory and went home, with Vietnam still in control of Cambodia, lol.
If China started a real war, like invading Taiwan or Japan, they would get their asses kicked and they know that, though they would never admit it. Their systemic short comings prevent them from doing much beyond their own borders.