I have a iPhone 2020SE how do I get Memoji

You'd need iPhone X, Xs, Xr, 11 or 12 to use Memoji. Your phone does not have Face ID, thus it does not have a True Depth camera and thus you don't have access to Memoji features on iPhone SE 2020.

olive243 wrote:

I have the new iPhone 2020 SE and I don’t know how to make my Memoji move when I move my face

Memoji's require Face ID which the SE does not support.

see >>> https://support.apple.com/en-us/HT209183