Setting an alarm for a specific date and time

Setting an alarm for a specific date and time. So android phones have a feature to set an alarm for specific date and time and the alarm keeps going off until you dismiss it. I have not been able to find anything similar in the calendars, alarm, or the reminders of the iPhone. You can set an alarm to repeat for that specific day but you can’t set an appointment reminder that’ll keep going off instead of one single note like it does in the calendar. That could be missed if you were away from your phone.