It depends on the circumstances. Conventional four-pin usb base, supporting 5 volts 2 amps 10 watts of power. If the qc2.0 fast charge technology is applied, the maximum power can be supported to 9 volts 2 amp 18 watts.
Of course, if usb compatibility is excluded, only as a quick interface, the actual power through it can be larger (mainly to increase the voltage).