Tiny characters are text, not a downloadable font

Characters such as ², ₓ, and ᵗ are individual Unicode code points. That is why you can copy them from a browser and paste them into a chat, profile, document, or spreadsheet without installing a font. They are not a CSS effect attached to the source page.

The trade-off is coverage. Unicode has a complete set of superscript and subscript digits, but only partial sets of letters. Punctuation support is partial too. The Unicode superscript generator includes a character table so you can see what is real before relying on it.

For ordinary sharing, this is wonderfully convenient. For equations, screen-reader-heavy content, or typesetting where alignment must be exact, use native math or rich-text formatting instead.