No it just use battery to heat the car. I got an Intens since last week and unfortunately we are actually in lockdown here in Milan but believe me air conditioning use the traction battery and mileage will suffer of if you use it in winter. I just had few time to check but this is what happens.
When it's in charge energy is taken from the charger so you can switch it on without problems even remotely from the app (a very bad piece of software).
R.