Building tension before the drop

Tension in a song is built primarily by withholding something the listener has come to expect, whether that is the full beat, a properly resolved chord or the eventual return of a familiar melody, and delaying its arrival just long enough that the eventual release genuinely matters when it finally does arrive in full.

Rising elements within the arrangement, a filtered sound gradually opening up, a rhythm section slowly thinning out, or a vocal steadily building in intensity, all signal clearly to the ear that some kind of release is coming, and that anticipation is precisely what keeps a listener's attention locked firmly in place during the build.

The eventual payoff depends almost entirely on how convincingly the setup itself was constructed beforehand, and a drop or release only ever feels genuinely satisfying in rough proportion to how carefully the tension before it was built, which is exactly why thoughtful pacing tends to matter considerably more than sheer volume alone.