Existing electricity generation goes to powering existing consumers. We'd burn those fossil fuels whether or not we bought more electric cars. Electric cars are a new electricity consumer. So the source of energy for this additional electricity is what matters.
In 2022, 83% of new electric capacity was from renewable sources. [1]
We can quibble about timing issues. For example, there's a lot of solar energy during the day but electric cars are often charged at night. But it's clear that renewable energy and electric cars are rising together.
1. https://en.wikipedia.org/wiki/List_of_countries_by_renewable...
Power plants can run at near constant rpm, and power thousands of households; inspections of emissions equipment and practices at that site can be enforced and fixed. Versus the same thousands of cars, a few have a check engine light on, a few have a leaking oil gasket, a few have a worn out ignition system, some of them bought contaminated gas. Any parking lot oil stain disproves you.
It's a good way to put the general wastefulness we exhibit with electricity into perspective though.