In the following essays, Nicolas Lardy, Senior Fellow of the Petersen Institute for International Economics, Washington D.C., explains why President Trump has been grossly twisted the truth in making his outsized claims –

China's Growth Is Slowing, but not Because of the Trade War (21 August, 2019)

China's Manufacturing Job Losses Are Not What They Seem (29 August, 2019) 

Are Foreign Companies Really Leaving China in Droves? (`10 September, 2019) 

In short, China's economy is slowing because of deepened economic restructuring, not because of the trade war, and not anywhere to the extent claimed. Since the trade war started, thanks to expanding trade and investments with other countries, job losses have in fact moderated and the number of foreign companies in China is by no means falling over a cliff.