As answered in the comments, it looks like this feature has a few names:
- Just an "eave", like any other eave on the house
- "eave return", or "full eave return"
- "cornice return" or "full cornice return"
- "closed gable"
There are a handful of colloquial terms for specific types of "eave returns" - "pork chop returns", "mutton chop returns", "bird boxes".
Sources: