Takeover
A takeover has a creator publish directly on the brand's account for a set period — a day of stories, an event's coverage. The brand borrows her voice for its own audience, the inverse of a sponsored post. Guardrails, approval flow and account access mechanics matter more than in feed deals, and credentials should never change hands loosely.
Worked example
A stylist runs the brand's stories for launch day via the platform's delegated-access tooling, with agreed topics and no password sharing.
Related: Whitelisting · Brief
Full context in the guides, or measure it yourself with the free tools.