Would carbon dioxide laser treatment be done by a plastic surgeon?

Yes: Many plastic surgeons do laser treatments as part of their practice along with surgical procedures.

If laser expert!: Physicians of many specialties perform laser surgery applicable to their specialty, such as ophthalmologists using laser for retina surgery, dermatologists for skin conditions, and plastic surgeons for operations where laser provides the best outcomes. It's not about the type of laser (or manufacturer), or even the specialty of the user, but the skill, training, and experience of the laser surgeon.