Apple generously refunded the full purchase price of my Chinese iPhone XS because I had evidence including dates, times and partial scripts, of not being informed about this key difference when I sort specific advice by calling Apple Support while working in China. It was a lengthy process and it took patience on both sides and without the evidence of being proactive in seeking advice I wouldn’t have been so fortunate. The dual sim in China is only available in the larger phone, not the Xs.