Scar type changes the approach, so consultation matters most here.
The laser makes very small channels densely across a scar, and as they heal new collagen forms so the depressed base rises. Depending on the scar type, an approach that ablates the surface and one that only stimulates below are used differently. Several sessions are assumed.
It is done in three to five sessions at four to six week intervals. The surface evens out over three to six months, because new collagen forms while the microscopic holes made by the laser heal and the scar floor rises a little each time. Splitting it up keeps the recovery burden lower.