Yes and no. It won’t make you more intelligent, but it will allow you to use what intelligence you have instead of letting it sit idle and undeveloped.
FYI, I never really played an instrument in my life. I tried to learn but I couldn’t. My intelligence is of a different kind, mostly involving visualization, spatial relationships, and numbers. I can’t play a chord, but I can calculate a chord segment. Music did nothing for me, but tearing stuff apart did.
Some kids may be able to exercise and strengthen their brain with a musical instrument, but some of us are better off with a toolbox or a calculator (a good one, like my HP48G) than with a piano or a clarinet.
@cazzie That may have increased their scores on standardized tests, but that doesn’t mean that they are actually more intelligent. Most definitions of intelligence I have seen are about the ability to recall and process information, but those tests are more about rote memory than critical thinking ability. I know many people who are quite intelligent but score low on those tests.
So who is smarter; the college grad who can recite all 50 state capitols but has no practical skills or the 9th-grade dropout who doesn’t know what a quadratic equation is but can rebuild a car engine without a manual?