China is different from Russia and the United States. China's war doctrine does not aim at occupying land, but at killing and maiming its opponents' field forces and destroying their economic and industrial strength. China also never fights security wars and usually withdraws quickly to end the war at home after achieving its objectives.
If China were to launch an attack, it would choose to reinforce and resupply the 54th Heavy Armored Composite Brigade stationed at Aksai Chin from the Karakoram Highway. Then launch a surprise attack from behind the Indian army attacking Pakistan and at the same time launch a surprise attack towards New Delhi. After destroying most of the Indian forces and destroying the entire industry, economy, infrastructure in the vicinity of New Delhi and dealing a serious blow to the confidence and reputation of the Indian central government, we would immediately withdraw to Aksai Chin and allow the Pakistani army to take over the Indo-Controlled Kashmir. There is nothing for the US to capitalize on.
If India is still unwilling to accept defeat, we can also keep bombing valuable targets in India until the Indian central government gives in. Or support local Indian forces for independent statehood.