Scope varies by how much of the campaign you need built, so there's no menu here. There are three shapes most of this work takes — each one can cover the full asset set or a single piece of it.
A defined campaign with a start and an end. Brand system work if it's needed, then the asset set built against it — video, display, social, landing pages, or whichever combination the media plan calls for. Right when there's a launch or a quarter to fill.
Ongoing production against a rolling calendar. Creative direction, monthly asset volume across formats, and iteration informed by what the last cycle's performance showed. Right when creative is a permanent, always-on need rather than a project.
Functionally an in-house creative department without the headcount. Campaign architecture, brand governance, production across every format, and a contractor bench pulled in as scope requires. Right when there's more marketing surface than internal capacity.
Most people aren't at first. Tell me what you're trying to launch and what your channel mix looks like, and I'll tell you honestly which shape fits — including if it's smaller than you thought.