An iPhone will not replace a proper camera let alone a mirrorless camera. Its ergonomics and features will never be able to match a dedicated camera. And do you really want to shoot on a device like this where it’s difficult to change settings on the fly?
But we do have to admit, the best camera is the camera that you have with you, and perhaps the iPhone 13 is the ultimate C camera, or good enough for someone who is outputting to YouTube only and wants to stay very minimal in their setup.