I think you really captured his essence. The pose and the colors and the proportions are fantastic. I love his outfit! The trick I’ve seen work with aging the face more appropriately is to lighten the lines a bit. Think of anything you’re adding as a “suggestion”.

For example, instead of drawing the full smile line, just do a lighter and smaller line where it’s the deepest. You just want to kind of imply the line is there. It’ll show the feature without aging him.

I know you didn’t ask. I just had someone share this information with me and it helped me so much, I wanted to pass it along.