Yes, makeup or concealer is fine to use on the new, pink skin that appears after the unwanted ink is lifted out. You can expect the new skin to repigment on its own just as it would if you had injured the surface of the skin and caused a scab to form as the skin healed itself. As a general rule, the lighter the complexion the faster the skin will take to repigment. Darker skin tends to be more sensitive, requiring longer time to repigment than lighter complexions.
Once the tattoo removal is complete, you’ll also be provided with a special ointment to use overnight that soothes the skin and helps it to return to your usual skin color more quickly.