What is the best treatment for sun damage and brown spots snd mild cystic acne scar removal on the face?

Several. Intense pulsed light (ipl) is really good for sun damage but especially the brown spots. Chiemical peels can work too depending on the damage as well as on some acne scars. Other acne scars may need lasers or certain type of in office surgical intervention.
Fractionated co2. For your condition the best treatment is a fractionated co2 laser treatment it will address the hyperpigmentation and acne scarring at the same time I have had great results in my practice with it.
Laser. Fractionated erbium or co2 will help acne scars as well as lighten sun damage and dark spots. The healing time is 4 days for erbium to about a week for co2. If the s ars are not an issue other lasers or light based devices can be used for the sun damage and brown spots without down time.