There is a valley near Anchorage, Alaska where the vegetables grow to ridiculous size during the summer months due to the Sun being up most of the time. I suppose if dragonflies lived in a totally oxygen saturated higher pressure flight regime, the deterministic DNA programming for growth might produce larger specimens than we see today. Or the sudden loss of the canopy could explain why creatures with expensive energy requirements in our current atmosphere went extinct?
Interesting questions! I’d like to see what an enriched 02 atmosphere would do for insects, etc. Of course, adding C02 to the plant life at much higher percentages might be necessary too.
I often wondered what the long term effects of intense sunlight are on organisms versus a more cloudy atmosphere along with increased oxygen and C02.