You can also use on your Mac.
Choose Keynote > Settings (from the Keynote menu at the top of your screen).
Click Auto-Correction at the top of the settings window.
In the Formatting section, select the “Superscript numerical suffixes” tickbox.
You can add buttons to the toolbar to quickly apply superscript and subscript to selected text.
Go to the Keynote app Create and use character styles in Keynote on Mac