It is possible to use two different rates (rate plans) when connecting to Booking.com.

Standard
This is a refundable rate (plan).
Your guest is able to cancel a booking on Booking.com without necessarily being out of pocket. The guest will be refunded in accordance with the cancellation policy you have set up.

Non-refundable
As the name implies, no money will be returned to the guest in the event of them cancelling their booking.
Non-refundable rates can be used to offer cheaper prices to your guests. Some guests prefer to spend less money over the knowledge that a refund will be available should they have to cancel their holiday.

A rate plan called Standard needs to be created in Booking.com as the minimum requirement for the integration to work.
A non-refundable rate can be used as a standard rate, if required