As for Iran, we can see if top Iranian officials will visit China recently. If top Iranian officials visit China, that would indicate Iran's determination to resist, and China would likely intervene to prevent a new Middle East war. If top Iranian officials do not visit China, then it means that Iran has capitulated and China will not intervene in the US invasion of Iran.
As for China, it is unlikely that China will have any negotiations or even contact with Trump until June of this year. Because there are a lot of actions that China can conveniently do only when the relationship is very poor.