type something, tap a style to copy it. these are unicode characters, not a font, so they paste anywhere that takes text.
each style swaps your letters for other unicode characters, like mathematical bold letters or circled letters. no font is involved, so the look survives copy and paste.
not every style has a unicode version of every character. anything without one is left as it is, so numbers and punctuation often pass through unchanged.
it works, but screen readers often read these characters one by one or skip them, and search will not match them. keep plain text for anything people need to find or hear.