Yep, they will simply program the cars to only take charges during certain periods.
Those periods will be August 1 - October 15.
Currently happening in Great Britain. New regs mandate that all new EVs have to be able to communicate with the smart meters also being mandated. The regs state that the supplier can curtail EV charging at any time so as to reduce demand on the grid. Can’t remember where I read it, maybe wattsupwiththat.