Here’s a great little trick I learned from my youngest daughters. If you are in the OSX mail app just hold down control-command-space and a window will appear full of emoji. Click any emoji and it will be added to your email. (Emoji are the little smiles etc that people put in emails. 😉)
Once you have the emoji in your email, if you want to make it bigger, just select the emoji and press Apple ‘+’ to make the font bigger.