So, if you have plentiful natural gas, then, yes, certainly, that's what you'll do; it's far, far easier and cheaper. China does not have plentiful natural gas, and is indeed building coal peaker plants.

Scroll through the last 72 hours here and you can kind of see it in action: https://app.electricitymaps.com/map/zone/CN/72h/hourly

Now, clearly, there's a long way to go, and China does still have a lot of baseload coal. But it's not building much if any _new_ baseload coal.

Think that's weird? France has load-following _nuclear_ plants (it more or less has to, given how much of its grid is nuclear).