Provoke Russia and Europe/USA into nuclear war. Let them destroy each other. Profit.
If you have close Chinese friends, they will surely agree this is a common idea in China and that something like this could happen. Some accept it as an abstract possibility, some actively hope for it. The latter type sounds like a Mexican nationalist in San Diego talking about Reconquista of the American Southwest.
A military thought experiment requires imagination. Cui bono?
China would definitely benefit in its battle for global dominance if Europe/USA and Russia all destroyed each other in a nuclear war. By many accounts, so would Israel.
If the two worked together to goad and facilitate war, Western neocons and others loyal to Israel could work their schemes within Europe/USA to provoke Russia, while Chinese operatives could work their schemes to facilitate Russia and provoke Europe/USA.
Much of what we see in the news supports the notion that something like this is happening. If Europe and Russia are destroyed in a nuclear war, Israel will be able to take over what is now Ukraine and more. Ukraine historically was part of Khazaria. Whether the Khazaria hypothesis of Ashkenazi origins is true or not, many believe it and many would welcome a Greater Israel of these dimensions.
As for China, a destroyed Russia, Europe, and USA would give them free rein throughout the world. No military power would threaten them and they could expand their borders as much as they wanted, especially to the north and northwest in what is now Russia.
By KOBK rules, a plot like the above is entirely natural and practicable. Whoever wins wins. It doesn’t matter how. Such a plot is also almost cost free and risk free. If the parties fail to provoke nuclear war and annihilation of their adversaries, no one will even know what they were doing. If they succeed in provoking the war, no one will be left to complain.