We can’t know if that’s true until the shooting starts. Nobody knew for sure how strong Russia was until they went to war in Ukraine. In fact, the people who were in the best position to know (the Russians themselves) clearly didn’t know because they never would have started this fight if they knew it would expose them as so weak.
We do know a bit about how powerful the US would be because they get involved in so many conflicts. But, even then, they haven’t really faced a near-peer opponent since… who knows when.
In any sustained conflict, the ability to keep feeding troops, food, and supplies to the front line would matter, and that’s where China might have an advantage. They have so many people they could keep feeding into the meat grinder. They have a huge manufacturing-based economy that could supply more and more arms and armour. One weakness is that they’re a net importer of food, which would be a problem if those imports were disrupted.
One thing’s certain, every country in the world is closely watching what’s happening in Ukraine and trying to learn things without having to put their own soldiers in the firing line. I’m actually sure that that’s one of the conditions for the military aid from the west. Sure, you can use these very modern weapons systems, but you have to turn on telemetry and share everything with us.
One lesson I’m sure they’re learning so far is that drone warfare is going to be key. They’re key for intelligence gathering, targeted strikes, artillery spotting, etc. A cheap drone can take out much more expensive weapons systems, and they allow a “pilot” to be very close to the action while not being in any danger. Because of China’s drone industry, they’d have an edge in that area.