I used an Alexa Routine to have my Amazon Smart Plug turn ON the heat in my chair (same as a light) for a fixed amount of time. (The chair heat plugs into an electrical outlet, so I inserted the Amazon Smart Plug between the chair heat plug and the electrical outlet.)
After setting up your Amazon Smart Plug, I renamed the smart plug to something meaningful. In my case I renamed it “Chair Plugs”. Then I changed the Amazon Smart Plug to Type = Light.
To create a Routine, I went to the Alexa App main menu and selected ”Routines” then selected the “+” in the top right of the screen.
My routine is as follows:
ROUTINE NAME: “Turn on my chair heat for 30 minutes”
WHEN THIS HAPPENS: “Alexa, turn on chair heat”
Add action:
Select:
1) Smart Home, Lights, Chair Plug, Next, Power: On
2) Alexa Say, “Chair heat has been turned on”
3) Wait, Duration is 30 minutes
4) Smart Home, Lights, Chair Plug, Next, Power: Power: Off
5) Alexa Say “Chair heat has been turned off”
If you are turning on anything other than light, I would suggest testing your routine with a light connected to your Amazon Smart Plug. This same routine will probably work with any brand of smart plugs.