I am not sure if he will get louder as he grows, but when I was a kid I had a sun conure that was louder than the one I have now. I think it just depends on the personality of your bird.
My sun conure I have now, Hotrod, can be loud at times. When I get home from work, he screeches out of excitement to see me. Also sometimes he will screech if you leave him by himself to go to another room when he is outside his cage. Other than that, he only screeches here and there every once in a while. I would say he screeches maybeeee 10%-15% of the time? He really is good at not screeching too much, and when he does I know it is because he is trying to tell me something.
Aside from screeching, as he grows older you will probably be able to teach him some things, or either he will pick up on certain sounds that you make. For example, Hotrod can say "step up" and "I love you." He also can imitate my laugh, coughing, do a kissy sound, and a high pitched hum I do to him.
He especially likes to show off his tricks at night. I put him in his cage (which is in the living room) for the night around 8pm, and if we leave our bedroom to go into the kitchen, bathroom, etc, he will start doing all of his tricks and all the noises he can make.

So, overall, as your conure gets older I think he will learn more things.. but all birds have different personalities!
