Pumped Desert Add-on 1.21+

From the name, you can guess that the mod Pumped Desert is dedicated to the desert biome of Minecraft. New mobs, structures, blocks, and items — the once lifeless and empty biome will be filled with new elements to make your time in the desert an exciting and interesting activity.

Mobs
Ostrich: can be tamed and bred with Wheat Seeds, and with a saddle, you can ride it
Rhinoceros: can be bred with Carrots. Horns can be crafted into a Rifle
Mummy: spawns at night and can clone itself
Tumbleweed: spawns randomly and drops Sticks
Fennec: can be bred with Eggs
Desert Turtle: can be bred with Sea Grass. Shells can be crafted into equipment
Sandstorm: spawns from Sand Giant
Sand Giant: appears from the Desert Altar when the player uses a Fire Charge on it. Close and ranged combat. Drops the Heart of the Sand Giant and 4 Desert Keys