In vanilla Minecraft, you cannot hatch the Ender Dragon egg
The dragon egg is only a trophy item after defeating the Ender Dragon
You can pick it up by clicking it after it teleports to a nearby block
If you want a hatchable dragon egg, use a mod, addon, or custom map
On modded servers or modpacks, follow that mod’s specific hatching method
In creative mode, you can place dragon egg-themed custom items, but not hatch the vanilla dragon egg