Yes, the smart plugs do have an always on component, but it is often a fraction of a watt. Various smart plugs are listed if you scroll through the linked thread, but I just quoted the KP115 since that is what you asked about:
I added a manual device to my Always On list named “Kasa” with location set to “Multiple” and estimated usage of 9 watts. It accounts for 15 energy monitoring smart plugs that are in use throughout the home at 0.6W each.