That's correct, my 4090 is running on 85% power limit and I haven't seen any noticeable performance loss aside few points in various benchmarks. But in my case CPU is the limiting factor in most cases, not the GPU. Waiting for new x3D to finally unleash the beast fully.Yeah, it depends from where the limitation comes exactly. However, with the 4xxx from what I've saw, you can save a power by limiting your fps or just the power draw itself without much performance loss.
quick example: about 55% power saved for 45% loss. This is by default, no custom tuning. Oh, an a bit of saving of the CPU, of course.