This unit will work with an external power adapter that uses voltage of 12-19 V DC depending on the type of power brick used. If the capacity is greater than 65 W it might harm the unit, so in that case it is recommended that you disable the "Power Sensing Circuit" feature (via BIOS option) when using an AC-DC adapter greater than 65 W.
If an adapter with more wattage can harm the NUC, there is something very wrong with the NUC design.
The voltage (V) should be the parameter observed, and any power supply with more than the minimum wattage (W) required by this NUC should be OK. So 60W or 6000W, there should be no difference for the normal operation of NUC or any other properly designed device.