It's never too late to improve your brain although there can be this false thinking that the brain needs "intellectual" hobbies to be healthy.
Yo give the most benefit, you should mix in hobbies like chess with things that stimulate your whole body and cause your brain to coordinate multiple systems at once. Something like dance is highly beneficial because you're not only listening to music, you're coordinating your movements, balance, emotions. If it's a social dance even better. You're coordinating your social skills as well.
I don't practice what I preach but I think social dance is the number one way to keep your brain healthy as well as your body if you're trying to be efficient.
I'm a firm believer that taking on something new every decade or so of life is an entirely good thing. I've watched so many people stop living in their 30s, 40s, and 50s. My heroes are people who keep doing what they love into their 80s and 90s, and keep finding new challenges along the way.
My understanding is that different types of exercises for your brain (chess, learning an instrument, etc) won't help prevent a decline, but that it might give you some tools to deal with it.
Is practicing chess at an adult age beneficial for the brain, or is it already too late?