20 Outback Limited XT 13 Outback 3.6R Limited
No, not a block heater. There is a supplemental electric heater to help the water used for interior heating get warm faster. Not sure if all trim levels have it or not. When it's cold, I noticed my 2020 Outback gets warm inside much faster than the 2007 it replaced or my wife's 2013. As far as battery drain, it only works when the car is running, and auto stop/start is disabled when the car is very cold.I think he's probably talking about an engine block heater, that runs off of 110v for folks in cold climates. I can't imagine there's any kind of internal heater run off of 12v to warm up the coolant. That would take an enormous amount of power to have any real effect.
My 2016 Ford F350 diesel has a similar system. Diesels are very efficient engines and don't generate as much excess heat as gasoline engines. My F350 gets warm inside in about 5 minutes. My 2002 F250 diesel without a supplemental heater typically took 15 to 20 minutes to get even moderately warm. The technology works.
It's mentioned in this thread: Heater blowing too hot air