All camera formats are a crop of some sorts relative to other formats. Look at Mediaum format...or even Large Format. In large format...a 135mm lens on a 5x7" plate camera gives an effective field of view as a 26mm lens on a 35mm sensor. So the effective "reach" on a smaller sensor is very relative. If you compare the larger 8x10" frame sizes of the largest field cameras...then a 135mm focal length compares to an 18mm on a 35mm frame. A standard lens on an 8x10 is a whopping 210mm. So in theory, if we had massive resolution plate cameras (silly expensive sensors) we could have one lens (a 70-200mm f2.8 zoom) that could cover silly ultra wide (1mm) to 300mm telephoto depending on our crop down size from the massive 8x10" plate to 1.6c crop sensor. The caveate here is that the 70-200 mm f2.8 would be massive due to the image circel requirement of the 8x10" plate camera...but the maths example stands as a theoretical possibility.
Back in the day when I used to run 1.62x crop to supplement my full frame camera bodies, I would use the same lenses on both cameras. An example of the crop maths, my 70-200 f2.8 LIS would become and effective 110-320mm f4 LIS. Or my ef 400mm f2.8 LIS became an effective 640mm f4 LIS. Then I realised that a simple 1.4x TC offered roughly the same effect at the long end, slightly shorter, but close enough. The difference being that the cropped body had a faster frame rate than my full frame camera, the AF was slightly superior natively than the full frame with a 1.4x TC and the files sizes were smaller and faster to edit en-mass. However, the 1.4 TC option was smaller, lighter and a lot cheaper.