The name of the Gutenberg block is Booking Form. It can be found in its own category/section called Five Star Restaurant Reservations. Alternatively, when you add a new block, you can just search for booking form and add the block to the page.
After adding the block, you will see a preview of the booking form in the page edit area.
If you have multiple locations enabled, you will also see an option in the right sidebar to choose a specific location for the booking form, which will remove the option for the customer to select the location and automatically assign the booking to that location.