Can you use a PS4 controller on a PS5? Yes, here's how

To use your PS4 controller on a PS5, connect it to the PS5 with a USB cable and press the PlayStation button on the controller.

How to upgrade your PS4 games to play on a PS5 with better graphics and frame rates

You can upgrade eligible PS4 games to play on a PS5 in higher quality through the PlayStation Game Hub and PS Store.