How do Fancy Fonts work?
Unlike actual font files (like .ttf or .woff) that must be installed on your computer, these "fonts" are actually just different character sets defined within the Unicode standard. Unicode assigns a unique number to every character, including mathematical symbols and ancient scripts that happen to look like stylized english letters.
Because they are characters and not styled HTML, you can copy and paste them safely into Twitter profiles, Instagram bios, Discord chats, and Facebook posts.