With your electric car plugged in, you can set the timer for when you want the car to be warm when you’re ready to leave. Any frost on the windscreen will be melted BEFORE you get in, this functionality can be set remotely. The car will be ready at your preferred temperature and, where provided, the driver’s seat and steering wheel will be warm too. Alternatively, the heating can be switched on manually while still plugged in.
On an Electric vehicle the Heating is carried out from the main battery, not wasted engine heat. Consequently, it’s better to provide the initial warm up from the charger rather than deplete the battery charge.
Preheating is part of Preconditioning, which can also be expected to warm the battery to make it work more efficiently, e.g. for Regenerating.
For an example see Nicolas Raimo‘s YouTube video