If the text is in a text box, table, or shape, first click the Text tab at the top of the sidebar, then click the Style button.
In the Font section, click keyboard shortcuts to quickly apply superscript or subscript to selected text. For superscript, press Control-Shift-Command-Plus Sign (+). For subscript, press Control-Command-Minus Sign (-).
If you want to make text higher or lower than the text next to it without changing its size, adjust its baseline shift.
, then click the arrows next to the Baseline Shift value to raise or lower the selected text.