I have not seen any evidence that Apple's chip is smaller, faster and more efficient.

Apple's CPU cores have been typically significantly bigger than any other CPU cores made with the same manufacturing process. This did not matter for Apple, because they do not sell them to others and because they have always used denser CMOS processes than the others.

Apple's CPUs have much better energy efficiency than any others when running a single-threaded application. This is due to having a much higher IPC, e.g. up to 50% higher, and a correspondingly lower clock frequency.

On the other hand, the energy-efficiency when running multithreaded applications has always been very close to Intel/AMD, the differences being explained by Apple having earlier access to the up-to-date manufacturing processes.

Besides efficiency in single-threaded applications, the other point where Apple wins in efficiency is in the total system efficiency, because the Apple devices typically have lower idle power consumption than the competition, due to the integrated system design and the use of high-quality components, e.g. efficient displays. This better total system efficiency is what leads to longer battery lifetimes, not a better CPU efficiency.

The Apple CPUs are fast for the kind of applications needed by most home users, but for applications that have greater demands for computational performance, e.g. with big numbers or with array operations, they are inferior to the AMD/Intel CPUs with AVX-512.