The iPhone 12 mini is the most interesting of the four new handsets announced by Apple at its October keynote. Up until now most of the lower-tier models featured parts from older phones, but the mini boasts a lot of the same hardware as the other iPhone 12 models. It's also slightly smaller than the current iPhone SE, but it is equipped with a larger display making it a faster and more powerful option for those who prefer one handed devices.
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.