You cannot hatch the Ender Dragon egg in vanilla Minecraft
The dragon egg is only a trophy item
In Java Edition, right-clicking or mining it makes it teleport
In Bedrock Edition, it also cannot be hatched normally
Use mods, addons, or commands if you want a hatchable dragon egg
Example command-based method: use custom mods or datapacks to create a hatchable egg
If you mean a different dragon egg from a mod, follow that mod’s specific hatching rules