I don't disagree on there always being one or more leaders. But the state is not "an agreement on how to do things" otherwise a family or companies would fall into that category. Any community with shared standards, really. The state is an apparatus of coercion. I agree that framing anarchy as the absence of rulers/leaders may be misguided, it's much better to think of it as a system of cooperation based on voluntary association. With that framework, most of our relationships are anarchic because we enter them and remain in them willingly. Our relationship to the state however is coercive, and thus not anarchic.