What is the plan for the massive unemployment in China when it decides to not sell lots of goods/sanctioned by the white and wanna-be white world?
If some other country sanctions China while China is defending itself from US' aggression war, that country has committed an act of war and would also be part of the battlefield.
Inside China itself, regardless of which countries are the aggressor parties, there would be a complete reorientation of industries, with major workforce mobilization, both for civilian and military purposes. You'd be left with many empty civilian jobs as people are instead helping with the war, so I strongly doubt unemployment would even be a thing at all.
Chinese response to a Taiwan invasion would perhaps, among the things we have seen in real life, most closely resemble the Covid-19 response. I don't mean lock downs in the cities (except within Taiwan), but the government is going to call up a ton of resources, civilians will set up funds to contribute, industry will be mobilized to create response equipment.
As the initial shock of the first US offensive has been blunted, China would likely attempt to form a coalition to impose economical blockades on US, with the goal of preventing US' replenishment by cutting off electronics, civilian goods and pharmaceuticals.
To totally cut off US, China would need to reach out to the other global sources of electronics, in particular South Korea, but perhaps spanning as far as EU countries as well. There would be an ultimatum to cease dual use goods supply to America, on the grounds of UN's law against invasion wars.
If that ultimatum is not obeyed, China will have to use even more people to man land fronts. Plus at this point, the creation of Ukrainian style "workshops" will arise in earnest, in addition to China's regular massive automated weapon factories. Such workshops would produce smaller drones, cluster warheads, mines etc, suitable for being lobbed a short distance on the Korean border (or inside Taiwan, if American/KMT soldiers still hold onto a foothold), rather than the true blue high end cruise missiles made in large government factories. That will take even more employment.
Tldr: undermanning jobs is a much larger risk than unemployment