These emojis including it’s eyes, whether or not it has arms, words, or other fancy decorations like stars (☆).

Simple Flat Mouths
( ^_^)/(^ _ ^)/(^_^)
(^-^*)/( ̄ー ̄)(∩_∩)
(∩▂∩)(☆^ー^☆)(v^_^)v
p(^-^)q