The correct way is to argue passionately that your country has committed the MOST war crimes/genocides/human rights violations. Ya know, bragging rights.
The worst accusation you could make about China's alleged warcrimes are how neutral they are in regards to Israel. They also sell guns to both sides of the Kashmir conflict, which isn't great. They have sold guns to Israel in the past as commerce, but that's a far cry from the west simply giving Israel weapons and intelligence for free.
Whereas the USA invades a new country on average every 1.5 years and has over 800 overseas military bases. China hasn't had an active overseas military conflict since the Vietnam war. This isn't a comparison at all.
If you want to boycott all the murderous sociopaths both foreign and domestic, you'll have to move into the forest, grow your own food, and either have your own grid or do without one all together.
Humans are the problem, fortunately for the earth and all the other life on it long term, we appear to be the final solution to ourselves. We'll make this rock unlivable for our very fragile bodies, the Earth will clean up after its failed mutation in a few million years just as it did after the trees of the carboniferous period caused an ice age, and beautiful homeostasis, that thing we refused to entertain, will be restored.
And nothing of value will have been lost. Too bad humanity largely genocided any cultures and gene pools that did live in harmony with nature, as they got in the way of our glorious metastasis.