Most of what applies to Word also applies to making PowerPoint presentations accessible.
One exception is headings. You don’t choose a heading style the way you would in Word. Instead, you use a built-in slide layout. The top text box is like a heading level one or two. Microsoft has a good summary of ways to make PowerPoint more accessible:
The best way to make an accessible PDF from your PowerPoint deck is with Adobe Acrobat. When you install that, you will find an “Acrobat” tab on the PowerPoint ribbon. Use that to save a tagged PDF.