You’ll need Gleam Club in order to put emojis on signs and in chat. They have to be entered as a code - two good resources for the codes:
In the game, @majorvex created a great gallery of them in Gyosha Mall - here is a thread for it, there is a how-to there as well - 
✅ Emoji quick reference gallery for everyone with codes displayed in-game
Online, @Soju-VB provided this list of codes for the emojis - 
https://docs.google.com/spreadsheets/d/e/2PACX-1vR03G7emdphWwe2DBCQoG0-97X63C8WvqqwVXjYFd8KKLkF-ycfqGSiZPGMFwlkS45et7c_xWkN7m2c/pubhtml#