If you know where to look, I'm quite sure you can already do this with vanilla ESP-IDF. I don't have a VNA or whatever is used to measure power at the antenna, but I do have a precision ammeter that confirmed my changes were effective at the supply. I only changed PHY power parameters and a lot more power was going somewhere.

Also, in my limited understanding, even changing the physical antenna can alter transmission power characteristics in such a way that it likely violates some limit, at least for some very specific wavelength or direction.