3DMark - Ice Storm Unlimited Graphics Score 1280x720 offscreen:

Apple A13 Bionic: 208697

RTX 2080 Ti: 521458

https://www.notebookcheck.net/Apple-A13-Bionic-GPU.434833.0....

https://www.notebookcheck.net/NVIDIA-GeForce-RTX-2080-Ti-Des...

Keep in mind the A12Z drives a 2732×2048 display, at 120Hz (iPad Pro). That is a beast to drive for the GPU.

A 2080 Ti can do 4K at 80fps (Rise of the Tomb Raider).

For another source, AnandTech says the A12Z is a Xbox One S class GPU: https://www.anandtech.com/show/13661/the-2018-apple-ipad-pro...