If you book a course, the rental fee is generally included in the course price. For dive trips, the inclusion of a gear rental will depend on the dive center. To confirm whether a gear rental is included in the listed dive activity/price, you can open the listing, and scroll to the bottom to see what is included in the price.
If you are not sure or have additional questions, you may contact the dive center.
If you need to rent equipment, the dive center will require your size, if you do not know it, just provide them with your height, weight, and shoe size.
If you booked a liveaboard, you can check on the boat page what is the price for the rental.