I doubt China would steamroll them. People thought Russia would steamroll Ukraine, it very clearly didn’t. Besides, China isn’t exactly a loved country, it has “allies” that would likely abandon them on the first opportunity and many countries that would love to see them getting kicked in the proverbial nuts.
Any militaristic action of China against any of those big targets would trigger a response from several countries. While everyone will talk peace, in reality a good portion would try to play the war up for as long as possible, to bleed both dry.