Yes, Clients should expect an increase in pricing according to the amount of finishing coats requested.
Level 0: Drywall is hung and attached to the wall frame
Level 1: Adds tape to seal the seams, and joint compound to cover the tape
Level 2: One coat of compound to the panels, usually for tiling
Level 3: Two coats of the compound for a smooth finish, ready for texture
Level 4: Three coats of compound, good for flat paint or light finishes
Level 5: The highest level of finish ideal for gloss or enamel paints