BYU can play in the playoff, the Cotton Bowl against the G5 champion, or the Hawaii Bowl.
To earn the Cotton Bowl, BYU would have to beat out Notre Dame and every other team after the automatic bids are determined (top 4 teams plus top remaining Big 10/Pac 12 teams to the Rose Bowl, ACC & SEC/Big Ten team to the Orange Bowl, etc, SEC & Big 12 team to the Sugar Bowl, etc).