This question misconstrues the purpose of an IQ test. IQ doesn't exist to provide a canonical
ranking of humans (and LLMs) according to intelligence. They're a diagnostic measure, intended to identify people who require supports. In that individual capacity, they actually have some value. Giving people the ability to "boost" their score makes about as much sense as giving someone beta blockers before taking their blood pressure.
Meanwhile, the "Mensa"-type fixation on the upper range of the IQ scale is a cringe affectation.