To do so would require all of the laptops tested to have exactly the same GPU and in the case of this review, a GeForce RTX 2080 Super Max-Q. However, the other laptops used have the likes of the RTX 2060 or GTX 1660 Ti. With such a difference in the GPUs, it would very difficult to isolate the differences in the CPUs.
It's exceedingly easy to get the same GPU. In most laptops it's also easy to get the same SSD, you just swap them out. Laptops themselves are complete systems, trying to isolate the CPU in a laptop is essentially a fool's errand.