This mod makes the ender dragon drop an elytra. Nothing else. No config, no settings, just ender dragon dropping elytra.
Enderdragon Elytra is also available on Modrinth: https://modrinth.com/mod/enderdragonelytra
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If you'd like your ender dragon to also drop a dragon head, consider downloading Enderdragon Skull: https://legacy.curseforge.com/minecraft/mc-mods/enderdragon-skull