It's not that simple. Besides implementing a SoftMAC, the blob is also responsible for setting up the PHY, so it would definitely be able to adjust things like transmitting power. See the part describing `esp_phy_enable()`.
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.
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.