Yes, you can control smart heating from a smart speaker.
There are Alexa skills for both the Nest Learning Thermostat and Honeywell Evohome multi-zone heating. Google Home also allows you to control both smart heating systems.
So if you have a Nest, you can tell Alexa or Google to turn the temperature up or down. You can say “Turn the temperature up 2 degrees” or “Set the temperature to 20 degrees”. Or you can ask about the temperature or humidity. Or you can say that you are leaving.
If you have a Honeywell Evohome system, you ask Alexa or Google to set the temperature for a particular room to the level you want. For example “turn the dining room down to 18 degrees”