Most sensors can be implemented in a way that enables self-calibration.

I'm oversimplifying it here, but the macro process is taking some known attributes and mapping them to what you are observing. For example, if you can detect people, and you know the average height of a person, you can compute where your horizon is, and where you should (or shouldn't) expect to see people in the FOV. You can do this with cameras, lidar, etc. When you have multiple sensors you can do a lot more to have them all sample an object in their own ways and converge on agreement of where they are relative to each other and the object.