Alternatives to Epic Boons

Source: Dungeon Master’s Guide p. 230

You might decide to grant one of the following rewards to a 20th-level character, instead of awarding an epic boon. These two options can be awarded to a character more than once.

Ability Score Improvement

The character can increase one ability score by 2 or increase two ability scores by 1 each. The ability score can now be increased above 20, up to a maximum of 30.

New Feat

The character gains a new feat chosen by the player, but subject to your approval.