In general it's recommended to have about 1 sq ft of ventilation per bird 24/7, but in hotter weather more is often necessary. In hotter climates it's often recommended to have most, if not all, of one wall as open wire mesh to allow heat to dissipate.
Is the patio cover solid (instead of...
Yeah I'm struggling to think of how to improve a prefab like this and coming up blank at the moment. It's just tough since there's not really any extra space above or below to work with.
Unfortunately that style of renovation won't work on this coop design, it's intended for the sort of prefab with a small coop unit in and above a slightly larger run unit. Basically it takes advantage of the full foot print of the unit plus uses the mesh walls to help add ventilation.
I know you probably don't want to hear it but that coop is pretty problematic, especially given that you live in a hotter environment. I don't see any ventilation in it, plus I don't see any way to raise the roosts much higher than the nest boxes, to encourage them to roost instead of sleeping...