Auto Elytra is a client-side mod for forge and fabric which will automatically equip your elytra when you go to fly.
Simply keep a pair of elytra in your inventory and fly like normal! Your chestplate will be automatically un-equiped and re-equiuped when you stop flying.
The mod depends on Fabric API or QSL if you're using Quilt. If Cloth Config API is installed then a configuration menu is accessible through Mod Menu or the Forge Mods menu.
This mod may be considered cheating on some multiplayer servers, use this mod at your own risk.