If you're asking "where do we get the power plants", that is a valid concern, especially as we want to get rid of coal power plants at the same time.
But ultimately it is not that much power - I did a back of the envelope calculation for my country and converting annual vehicle-miles driven into kWh with average EV efficiency ended up adding 11 % increase in electricity consumption.
Not sure how it stacks up with other countries, and yes, we need more and cleaner power, but 11 % increase is not insurmountable problem.
If you're asking "how does that much power gets places", electric trains routinely run as much power. My city runs hundreds of trams that take over 700 kW each, and full power electric locomotive usually takes about 5 MW. The grid already knows how to handle it.