Switch

A setting that takes effect the moment it is flipped. If the change needs a Save button, use a Checkbox.

Switch = applies immediately. Checkbox = submitted with a form. Never mixed in one group.
Instant and harmless is a bare switch; instant and consequential applies immediately plus raises an undo toast.
Never put a Switch on a staged screen that has a Save button.
Entitlements gate the control: unavailable on this plan means disabled with an upgrade hint, not a sentence beside a live switch.