The bank has two full-size USB-A ports, one USB-C and one microUSB. You can get 18W output from the USB-A and USB-C ports. The battery also has a low-current mode for small gadgets (e.g. smartwatches or Bluetooth earbuds) which have trouble charging from some power banks – this mode can be accessed by tapping the power button twice.
The Xiaomi Mi Power Bank 3 itself can be charged at up to 24W using its USB-C port. If you have a 30W Xiaomi fast charger, for example, the battery can be filled to 100% in 7.5 hours. The microUSB input is limited to 18W.