WattageViewer shows in the top MenuBar how many watts of charge are being supplied from the charger to the MacBook.
USB Type-C standard charging is complex and varies depending on the corresponding conditions of the adapter, cable,
and device itself.
If the device is not powered properly, it will waste battery power and degrade performance.
Also, powering with higher wattage can charge the battery faster.
You can always see how many watts your device is powered by from the power information residing in the MenuBar.