I get the dragonfly analogy, but fwiw...

During the Carboniferous and Permian periods (385.9-251.9 mya) the oxigen content of the atmosphere was much higher than nowadays. That allowed for gigantic insects to thrive.

Among them, the largest insect know to have lived was in fact dragonfly-like. "Meganeuropsis permiana" was ~17 in (~0.43 m) long and with a wingspan ~28 in (0.71 m).

Not sure if that qualify as "massive", but those where some pretty fucking big "dragonflies" the size of a medium-sized bird.