You can use any 5V USB charger, and it will work. But the original one supplied with Oppo Find X2 Lite says: 5V 2A (10W) or 5V 6A (30W). So I would say that Oppo has a proprietary rapid charging protocol that probably only works with certain cables and chargers, as 5V/6A is not really allowed as per USB standard. There's no guarantee that if you buy another non-oppo 5V 6A charger that it will rapid charge. Attached pic of AU/NZ supplied charger.