The role varies widely. Typically, there is a lot of administrative work required to manage the cadence of an exec team: Examples - collecting tracking metrics

The role varies widely. Typically, there is a lot of administrative work required to manage the cadence of an exec team: Examples - collecting tracking metrics ahead of meeting, tracking action items for completion, preparing materials for customer briefings, etc. A chief of staff helps the CEO get higher output by letting them focus on the decisions and not the process.