The level of a person’s raw intelligence, as measured by aptitude tests such as IQ scores, is generally stable for most people during the course of their adulthood. While it’s true that there are things you can do to fine tune your natural capabilities, such as doing brain exercises, solving puzzles, and getting optimal sleep – the amount of raw brainpower you have is difficult to increase in any meaningful or permanent way.
Source: https://www.visualcapitalist.com/12-ways-smarter-mental-models/