Can disguise self hide an Aarakocra's natural wings because they are hiding as a "different race"? Would this allow a creature to create wings to become an Aarakocra? If a creature has wings and hides them, would they be revealed if used in flight? If a creature manifests wings while under disguise self's effects, would they need to recast it to hide them?
It can make the wings look like a different limb, but your Aarakocra is stuck with 6 limbs.
Disguise self says:
You can't change your body type, so you must adopt a form that has the same basic arrangement of limbs.
The phrase "same basic arrangement of limbs" indicates that an Aarakocra with 6 limbs using disguise self must have 6 limbs.
You can probably work around this with some creativity and generosity from the DM.
Disguise self also states:
You make yourself--including your clothing, armor, weapons, and other belongings on your person--look different
This leads me to believe we should be able to conceal the extra limbs with some sort of pack on our back. As a kid I read a book about a young girl with dragon wings who always wore a back pack to hide them. Disguise self should be able to produce a similar effect, but your mileage may vary depending on your DM.