Really sorry to hear your child had a traumatic injury. I have a facial scar and I would advise going to the best facial plastic surgeon you can find. If needed, they can do a scar revision to help minimize the appearance, particularly if it was initially sutured in an ER and not by a plastic surgeon, then use silicone gel or sheeting to cover it. Then later once the scar is completely healed, you can do laser treatment to improve the scar texture. You also need to avoid sun exposure, so sunscreen and hats even in the winter (small blessing that it's winter, not spring!). And it's really important after a scar revision to keep your hands off of it and let it heal. Seems obvious, but I have a spot where I accidentally bumped the scab and it's noticeably less smooth even a decade later.
With facial scarring, I'd want the most skilled surgeon over a lesser surgeon that specializes in pediatrics. Ideally you'd find both in one, but that's what I'd prioritize if my child had an injury like mine.