I agree there must be some research on this. But also take into account why they are that heavy. Is that because of their length, or just because they are fat or muscular.
You should compare two riders with the same kind of built and same kind of muscle type. And my experience what I see around and my feeling says that length and weight don’t matter that much for well trained cyclists and that it is all about watt/kg.
So yes it is easier for a 60kg dude to put 300watts if he is better trained that a 80kg dude putting 400watts.
Just take a look at the past TdF / Giro / Vuelta winners, most of them are 180+cm. Not that small I would say…