Yes. For all headshot and portrait sessions, an appointment is required, with a deposit needed to hold your session date and time.
If at all possible, try not to wait until the last minute to book your session, dates can fill up fast.
I know that sometimes life happens and there you may need to reschedule your appointment. If that happens, and you reschedule your session within 30 days of the original session day, your deposit will apply for the new day. Otherwise it is forfeited. A no call no show is an automatic forfeit of your deposit.