https://www.theverge.com/2018/6/28/17506010/apple-ios-12-imessage-how-to-make-memoji

With the launch of Apple’s iOS 12 comes Memoji. It’s essentially the personified version of Animoji — you can design your Memoji to look like you and then use it to send silly videos or photos. Keep in mind that for now, you need to have an iPhone X running iOS 12 to use Memoji. Still, you’ll definitely want to play with it, and here’s how.

You can only access Memoji through iMessage. I wish this wasn’t the case, but it’s what we got. You’ll have to tap on the Animoji icon (the little monkey). From there, you’ll want to scroll all the way to the left and tap on “new Memoji.” This will launch the Memoji maker. The process is relatively self-explanatory. You’ll be able to choose your skin tone, which ranges from the expected to more alien choices, like blue and pink. You can adjust your hairstyle, eye color, head shape, nose, and lips. You can get more personal by picking freckles, facial hair, earrings, headwear, and glasses. I will say as a human that wears glasses, the options aren’t great. But you should be able to pick something relatively similar to what you wear now, and if not, well, hopefully Apple will give you more to choose from in a future update.