Holgas do it on their own, along with other possible random light leaks.
If you want similar darkened corners from regular negs, just add a little burn time under the enlarger, moving an appropriately-shaped (circular for 6x6, oval for 8x10) dodging tool up and down during the extra exposure. an extra 10% is subtle, 20% is more obvious. Test to taste from there.
Burned-in corners were very popular several decades ago, particularly for glamour shots. So, doing it with current prints can give sort of a retro look.