Light propeller aircraft usually do, but commercial jets aircraft do not. That's a matter of flicking switches in the right sequence and at the right time, but no ignition keys are involved. Despite the lack of a key, getting into a cockpit is not easy. Commercial pilots are checked at several stages before they can enter the cockpit, usually with identity cards which must be swiped at key points. When he appeared not to know how to buckle the seat's chest-harness belt, the pilots smelled a rat and called in the cavalry.

Source: Stuff February 24, 2019 18:56 UTC