Their motivation is self preservation. Western democracies make it pretty clear that they do not support the existence of brutal dictatorships. Thus brutal dictatorships are motivated to act in ways that can weaken the western democracies.
For China? World domination for Han Chinese, nothing less. They are taking over entire countries by "debt relief" aka loan sharking, and leaders who don't want their "investments" simply have their assets taken away by force like the Philippines.
Both can only follow through with their plans if there is no united opposition against them. Europe is falling apart on a national level with nationalist, often Russia-backed anti-democrats spreading discontent and hate, and the US is collapsing in ethnic and class war.
To what end? What is their motivation? They’re evil cartoon villains and hate our freedom? What’s their gain?