No, any iPhone 11, iPhone 11 Pro, or iPhone 11 Pro Max cases do not fit the iPhone 12 series.
Being able to reuse your old iPhone case on a newer model depends on a few different factors. Not only does your new device need to be the same size as your older model, but the cutouts need to match the camera, buttons, and ports.The iPhone 12 has launched in 4 different models with updated cameras. More importantly, the case of the iPhone 12 series has a square edge. The design is similar to the iPad Pro or the iPhone 4, and markedly different from the rounded iPhone 11.
Because of this redesign, iPhone 11 cases or iPhone 11 Pro cases will not fit the iPhone 12.