I have been experimenting a little with undervolting and overclocking the GPU by using a software called LACT.

To install LACT, go into desktop mode. Search for the flatpack LACT and install it. Open the software. Enable overclocking inside the app (it will give you an error). Close the error and close the app. Then reboot. Upon reboot, go into desktop mode and open LACT again. You can now use the overclocking settings for the GPU.

I have set mine to -100mV on the core (undervolt) and +100Mhz for the core (overclock).
Then I played some 4k Tomb Raider GOTY, and also ran some 3Dmark stresstests. I ran Steel nomad and Fire Strike ultra stresstests and both came back with a pass at 99.7% accuracy.

I have also tried to overclock the memory with +50mhz (to 2300 instead of 2250), but that did not seem to be stable and came back with an error in God of War rather quickly.

Running a 3Dmark firestrike results in a small uplift in performance. Which is in line with the increased coreclock speed (4%, 100mhz).

What I can also say from my testing is to not enable "Game Recording" as it is an absolutely performance killer. So only activate it if you really need it.