This question already has an answer here:
In the Unearthed Arcana "Feats for Races", the Dragonborn feat "Dragon Fear" states (emphasis mine):
Instead of exhaling destructive energy, you can roar and expend a use of your breath weapon to force each creature of your choice within 30 feet of you to make a Wisdom saving throw...
Now, I know this is only Unearthed Arcana and not "official rules", but the wording of this, to me, implies that it's possible for Dragonborn to have multiple uses of their Breath Weapon. However, reading the PHB about Dragonborn, they can only use it once per rest (I can't remember if it's short or long rest, I don't have the PHB in front of me, but it's irrelevant to my question).
So, according to either official rules or other Unearthed Arcana articles, is there a way for Dragonborn to be able to use their Breath Weapon more than once per rest?