In Bedrock 1.13 (and 1.14 for (legacy) custom skins) equipping a cape and then an Elytra will use the Cape's Elytra texture. (Reposted so image is easier to see) : r/Minecraft
Marc Jones on Twitter: "Capes! The capes and their use for elytra is possible with Minecraft Persona in #Minecraft 1.13.0.9. However, they cannot be added to custom Persona Packs, since each cape
Wavey Capes Mod (1.19.3, 1.18.2) - Make Your Cape Looks Special - 9Minecraft.Net