*OPTIFINE IS REQUIRED*
In order to obtain these variants, you can rename an Elytra in an anvil to have the keywords:
Shark
Priestess
Detective
Phoenix
Reaper
None of the keywords are case-sensitive, and you can even add more words. Example: Names like "Wings of Phoenix" or "Detective cape" will still work as long as you use the corresponding keyword.
(You can view each texture and their corresponding keywords in the Images)
Note: You can even use this with my other packs, "CouncilRyS Capes", and "HoloAdvent Capes" to have all the HoloEN capes, or even with "HololiveID Capes" to have all of my Hololive themed Elytras!