Arcanum Draconique
The oldest and most powerful dragons were mighty spellcasters, and this trait has been passed down through the ages to you.
You can choose a cantrip spell of your choice from the sorcerer spell list. Charisma is your casting modifier for this spell.
Your spell list for your class includes all dragonborn-specific spells . Add these spells to your class spell list. You still have to prepare them or choose them as dictated by your class, but they count as spells of your class for you.
If you do not have spell slots, you do not benefit from this trait, except for the sorcerer cantrip. If you take this trait and later gain spell slots, you benefit from this trait as expected.