Is it impossible for existing digital cameras such as ARRI ALEXA to reach 4K? Where is the red epic? Is this the only movie that can surpass 4K?

At present, the F65(6K, 15+ file) of Sony, the world's top digital camera, has exceeded the specifications of film. Resolution is not the main criterion for evaluating a camera, but tolerance or dynamic range. Although Alexa is only 2.5K, its tolerance reaches 14.5, which is consistent with the film. The epic barely opened the HDR file 14.5, but the red epic dragon file 16 is beyond the tolerance of the film. By the way, the bottom scan of film 1: 1 is about 2.5K