The short answer is

Have you tried tuning vocals in Audacity? Share your results (or horror stories) in the comments below!

Audacity does not come with a built-in, one-click "Auto-Tune" effect (like the famous Antares Auto-Tune or Celemony Melodyne). However, you can absolutely achieve pitch correction—from subtle tuning to the extreme "T-Pain" effect—using free plugins and a few clever workarounds.