I have mild acne, redness, a superficial scar and a prominent smile line i wanna try fractional laser but im worried. does it damage the skin ?

First things first: Before you consider doing any of this, get your acne under control with topical benzoyl peroxide and/or retinoic acid. If needed, your physician can add something else. Then, ask your twelve closest friends (some of each sex) whether you should have the scar / "smile lines" lasered. Most will probably say, "Huh?" For a 21 year old man, looking good is about physical fitness, not face touch-ups.