The OnePlus 9rt supports other chargers for charging, but not necessarily fast charging, and the charger must be adapted to the fast charging protocol to meet the requirements.
The OnePlus 9RT is certified as MT2110, supports 65W fast charge, and comes standard with a charger with output power of 5.0VDC, 2.0A or 10.0VDC, 6.5A MAX.
The OnePlus 9RT standard adapter is still compatible with PD, QC and other fast charging protocols, and can be charged for other devices that support fast charging. Whether it is for business or travel, only one charger is enough.