There is no Memoji or Animojis for the 2014 iPad Air 2 or the iPad Mini 4.
They lack the higher end Face ID cameras in other much newer iOS devices.
Also, Memoji and Animoji Stickers, for iPads that can run iPadOS, requires an iPad that has an A9 CPU or greater.
The iPad Air 2 and iPad Mini 4 models ONLY have A8X and A8 CPUs, respectively, and are ineligible from getting the Memoji Sticker feature of iPadOS.
For very good, third party Memoji apps for yout iPad model, I recommend either Emoji Me or Your Avatar Creator.
Both can be used with the iOS Messages app.
My Memoji that I use here in these Apple product support communities was created by Emoji Me and modified using Pixelmator for iOS.
Good Luck to You!