Hello.
- You can configure the list of time slots for booking for specific time at the Booking > Settings > Booking Form page. One of the time slot can be option to book entire day from 00:00 to 23:59. You can configure all these options at the Booking > Settings > Booking Form page.
2. Please note, in case if you need to make the booking for several different dates, and need to book specific time slots (not entire day) on these selected dates, then such functionality available in the Booking Calendar Business Small or higher versions. You need to activate the “Multiple days selection” mode at the Booking > Settings General page in Calendar section and enable this option: “Use selected times for each booking date“,if you want to use the selected times as booked time slots on each selected date. Otherwise, the selected times will be used as the check-in time for the first date and check-out time for the last date of the reservation.
Read more about the main features and small description about how to configure them here: https://wpbookingcalendar.com/overview/
Also check useful info at the FAQ here https://wpbookingcalendar.com/faq/
Kind regards.