Recently, I found one of the CWNP Question of the Day (QOTD) problems, with a VERY misleading answer..
I don't remember the exact question, but generally speaking the answer to the question implied that the same chip set, in two different Wi-Fi products, always generates the same output power level. This is incorrect..
That may be true when the devices use the same chip set FIRMWARE inside. This is often seen in products that are built inexpensively, or in relatively small numbers - meaning hundreds of thousands.
However, chip set manufacturers can supply much more. Usually it's only a usually free generic driver to their business partners. You buy some number of radios, and you get a copy. To misquote Popeye, if you're old enough to remember that cartoon character, "it does what it does and you don't gets no more".
Another version may be available at a relatively small expense. It has a number of hooks in it, that can be set by the product manufacturer. At the extreme end of possibilities, their are firmware development packages with very expensive source code and licensing options. Which if you also make, meaning buy, more than say a million radios a year, the chip set people may deign to provide you with some amount of access to their engineers. These last options may start at $50k-$80k and could go up into hundreds of thousands of dollars.
Regardless of the price, manufacturers often find the engineering access they were promised, to be VERY sadly lacking.
Each radio produced under the latter arrangements, MAY be programmed to emit different power levels, on different frequencies, with different modulations . This is all within constraints of course, including those dictated by country's regulatory agencies, and whether a Power amplifier has been added to the package, etc.
Obviously, a quality product sold in over 100 countries, requires many more builds than one used only in a localized version. Smaller companies often produce only one version, with a lower power level, that can be sold in several countries. It can be VERY expensive to certify equipment in multiple countries.