will the increased requirements to charge all these vehicles increase power plant emissions worsening the effects of coal over regular vehicle emissions?
No, that's never going to happen. A huge coal power plant is always going to operate at a higher efficiency than a little engine inside a car or truck. It's the efficiency of scale. And that's the starting point! Our grid is already nearing 50% renewable in some places and it's rising.
The Nullarbor plain recently electrified with charging stations at enough chip shops that you can drive Perth to Melbourne on a dinky electric car. The electric generators are powered by waste oil from the chips.