Consider someone has dragon's breath cast on them.
Until the spell ends, the creature can use an action to exhale energy of the chosen type in a 15-foot cone.
What happens if this creature exhale energy on targets inside an antimagic field?
Does the effect pass through as if it were a dragon's breath weapon?
An anti magic field does prevent the Dragon's Breath spell from affecting targets in an anti-magic field. In the spell's description, it says
You touch one willing creature and imbue it with the power to spew magical energy from its mouth...
(Emphasis Mine)
This shows that this effect is intended to be magical, and therefore does not work in an antimagic field, where
Spells and other magical effects, except those created by an artifact or a deity, are suppressed [inside] and can't protrude into it
