Copy and paste fancy text fonts with mathematical bold, cursive script, small caps, and decorative frame wrappers.
Most of what people call fancy fonts is one block: Mathematical Alphanumeric Symbols, U+1D400 to U+1D7FF. It was added so equations could tell a bold x from an italic x from a script x, and it happens to contain fourteen complete Latin alphabets, bold, italic, bold italic, script, bold script, fraktur, double-struck, bold fraktur, and sans-serif in four weights, plus monospace. Digits exist for bold, double-struck, sans-serif, sans-serif bold and monospace only, which is why some styles restyle your numbers and others leave them plain. Because the block is part of the standard, every current operating system ships at least one font that covers it.
The remaining fancy fonts come from three other places. Circled letters are Enclosed Alphanumerics (U+2460 onward) for the outlined set and Enclosed Alphanumeric Supplement (U+1F100 onward) for the filled circles and both squares. Small caps are not a font at all. They are borrowed from the IPA and Phonetic Extensions blocks, one letter at a time, which is why there is no Q. Fullwidth forms (U+FF01 to U+FF5E) exist for East Asian typesetting and give the wide-spaced vaporwave look. Knowing the source tells you the coverage: mathematical alphabets are safe everywhere, enclosed letters skip punctuation, and the phonetic small caps are the first to fall back on an older device.
Unicode only defines digits for five of the fourteen mathematical alphabets: bold, double-struck, sans-serif, sans-serif bold and monospace. Script, italic and fraktur have letters only, so digits pass through unchanged.
Yes, exactly. A bold x in a LaTeX equation and the bold x in your Instagram bio are the same code point, U+1D431. That shared origin is why the support is so wide.
You can, and they will render if the document font covers the block, Cambria Math and Segoe UI Symbol do. If you want the look without relying on that, use the Colour text copy format, which sends a real font-family instruction instead.