Yes and no.
The garbage collection system itself won’t pick them off, but that is always true because all Actors are referenced by the Level’s Actors array.
When you change levels the Actors will be explicitly Destroyed as part of the level load process and the references in your TArray will be set to null. There are some ways to transition Actors between levels if you are using seamless transitions (see GetSeamlessTravelActorList on GameMode), but that isn’t a commonly used mechanism.