Neurology has proven numerous times that it’s not about the size of the toolbox but the diversity of tools within. The articles starts with cats can’t talk. Human can talk because we have a unique brain component dedicated to auditory speech parsing. Cats do, however, appear to listen to the other aspects of human communication almost, sometimes much more, precisely than many humans.
The reason size does not matter is that 20% of brain volume accounts for 80% of brain mass in the cerebellum. That isn’t the academic or creative part of the brain. Instead it processes things like motor function, sensory processing (not vision), and more.
The second most intelligent class of animals are corvids and their brains are super tiny. If you want to be smarter then increase your processing diversity, not capacity.