Why does an alcohol-based perfume often bloom loudly right after spraying?

Answer: Fast carrier evaporation

Extra fragrance oil — More fragrance oil can increase strength, but it is not the special job of alcohol. Many sprays use ethanol because it dissolves the concentrate, lets the atomizer lay down a thin film, and then dries quickly. That exposes a larger surface of volatile fragrance materials, so the opening headspace builds fast. Oil formats can last longer yet stay closer to the skin, which is the opposite tradeoff.

Fast carrier evaporation ✓ — Right: alcohol is mostly a volatile carrier, not the long-lasting part of the smell. Ethanol helps make a sprayable, even film; once it evaporates, the fragrance oils are left spread over the skin rather than sitting as a wet patch. The counterintuitive part is that the thing that makes a spray feel big can also make the opening burn off faster. Projection and longevity are not the same feature.

A stronger base note — A stronger base note usually makes the drydown last, not the first seconds after spraying. Base materials are often less volatile, so they do not leap into the air as quickly as alcohol and top notes. The loud opening of a spray is closer to aerosol physics plus solvent evaporation than to a heavier ingredient shouting louder. A deep base can be persistent while still beginning quietly.