Yes, in the case of Bitcoin, we use a noisefloor called the difficulty and a signal called PoW, in order to coordinate on whatever it is we need to run our consensus-rule-set against to come to the same conclusion globally (on a probabilistic basis over time).

Some of the subsequent rules are aplied on a block level, where technically that is not even required; simply because consistent rule-application on a mess (blocks with utter garbage) would still yield the same results among everyone that applies those same rules.

Nakamoto consensus already is the DOS protection.