I have the HS200 smart switch. When I first install the switch I was able to dim the lights. I dont know when the kasa software or firmware upgrade I cant dim it anymore.
The kasa software has the icon with a light and circle which I use the circle to dim the lights. I am 100% sure I was able to dim the lights. I done it since day one. I dont know when that change. People keep telling me its HS220 that has that feature.
THe HS200 has that feature too on the software side not the switch itself.