For example, is a Black Dragonborn able to use its Breath Weapon, in this case, of acid type, to corrode walls, doors, objects, etc?
I'm asking this because when it comes to spells, they don't affect the environment unless it is specifically said so.
Best Answer
RAW - No, it only affects creatures
The Dragonborn race feature breath weapon is specific in what things it damages (my emphasis):
There is no language in this that suggests it would affect objects. You can compare this against spells like fireball which state:
Also note that the spell dragon's breath contains the same limitation as the breath weapon for the race with no allowance for object damage.
But what if?
The problem with allowing it is you've now increased the ability of the feature, and possibly of the similar spell effect that emulates the racial ability. Is it always on like fireball? Do they get to choose? Allowing this as a creative use will be up to a DM to determine, but doing so may raise questions rather than solve problems.