In case you also didn't know, it's the same process as colored text in chat.

Just write something and put § before with a character next to it.

For example, §L to make a text large, or §M to make it red

So.. writing §L§MHeart would Write Heart in a large font and colored in red.

Doing this on a sign or in chat will work and, today, I also found out you can do the same thing with name tags!