Are there established studies on using creative/artistic activities to improve mental health and well-being?

As an Art and Photo Therapist and painter I have shared the benefits of art-making with many people and seen awesome results. There is so much research and evidence that visual art (not to mention music or other art forms) increase self-awareness, self-confidence and calmness. It also often allows for processing of feelings and emotions as well as opening options and alternative ways of viewing our lives. More information at https://arttherapy.org/ and https://sharonsanborn.com/ Check out https://zentangle.com/ and/or https://www.soulcollage.com/ for fun ways to experience the benefits of visual art-making.

I always sang but never played a musical instrument until I turned 55, when I started taking clarinet lessons, having always loved that instrument's woody sound. I swiftly recognized that at least at that age, I did not have the finger dexterity for clarinet virtuosity. I also realized that I actually preferred low tones to high tones and harmony to melody: voila, I switched to the BASS clarinet, whose parts are simpler (as usually are the parts of larger instruments.) 19 years later. I now play my bass clarinet with the local university's Symphonic Band and clarinet choir. Playing music with others is one of the great joys of my life. It includes aspects of the creative, the physical, the mental, the social, and the breath. I heartily recommend that one take up an instrument AT ANY AGE. It will help to keep you ageless!

https://www.psychologytoday.com/us/blog/arts-and-health/200901/art-and-mental-illness-stop-the-insanity
https://www.ncbi.nlm.nih.gov/pubmed/21749556
Again personally have seen my daughter turn to art when she is "troubled" and anxious and it has always made her feel better :)