Superscripted ordinals are tiny and hard to read. So the best policy is to avoid them. To do this, you have to adjust your word processor’s default behavior.
In HTML, nothing will be superscripted unless you put it in a
<sup>tag. And there is no reason to do so.
Some fancy professional fonts (see font recommendations) include specially designed superscript alphabets and alternate figures that remain legible at small sizes. Those are fine to use in ordinals, but they’re typically made available as OpenType features. So you’ll still want to turn off any automatic ordinal shrinking performed by your writing tool.