Hi,
@FunkZ brought up a interesting thing and by my experience, memory speeds/latency do impact a lot, more than actual memory size, not even mentioning dual channel.
To be honest, its hard to say that a 6700XT will need to do, always, 12k. Firstly, because there are substancial diferences between AIB cards. Example: You won't find a cooler, as in temperature, than the RoG Strix. In turn, this could allow it to go further where a dual fan "wimpy" heat sink card will struggle to keep pace.
Then theres other components at play. 16gb 3600 CL14 should blast away 3000, in some extreme cases it may be a 10fps difference in games. Is there a quality PSU behind it, 80+ Bronze is not a good standard as in today.
Are others OC'ing? They might. Specially if they have a good AIB card with a good cooler.
And finally, your CPU could be bottlenecking the GPU a bit, hence the power limit looking hard locked.
Try the following:
Use curve optimizer to bump a bit the CPU performance and check if results get better, monitor closely the power draw of the GPU, if it increases, you found whats pulling you back.
Good Luck
The Englishman