Though the Suzuki method is designed towards young children, it is not the only way to learn to play music. And growing older is certainly not a reason to not start learning an instrument, whether you’ve learned some before and just fell out of the habit, or if you’ve never started. For adults, their patience more than makes up for a supposed “lack of plasticity" that comes with age. Learning an instrument at 5 or at 50 will be difficult, but not impossible.
Learning an instrument at any age will work your brain and body. Don’t be afraid to start now and learn an incredible skill!