Initial details on the GPU that Google has chosen for the Pixel 6 and Pixel 6 Pro have leaked. The GPU should represent a significant increase in performance compared to the Adreno 620 in the Pixel 5, and may be on par with the GPUs in the Exynos 2100 and Kirin 9000.
https://www.notebookcheck.net/Google-Pixel-6-and-Pixel-6-Pro-GPU-details-emerge.541252.0.html