Succession plans exist so a key person leaving isn't a scramble.
Creating a plan (Admin/HR): set the position title, current holder, priority (low, medium, high, or critical), target date, and notes, then add candidates.
Managing plans: view, edit, or delete from the plan list, filter by priority or status.
Who can do what: creating, editing, and deleting a plan itself is Admin/HR only. Managers can update candidate readiness and remove a candidate from a plan they're involved with, they're not purely read-only, but they don't create or delete the plan structure itself.