https://wccftech.com/ps5-dualshock-5-controller-ps4/

Sony’s upcoming PS5 DualShock 5 controller will also work on all PS4 models, if PlayStation France is to be believed.

The official PlayStation France website features a model comparison page that compares the individual PS4 models, including the original PS4, the PS4 Slim and PS4 Pro. While most of the details are publically known, the page also mentions that the upcoming DualShock 5 (DS5) controller for the PS5 will be compatible with all of the PS4 models.