I construct enclosures with the intent they will deter stray dogs/coyotes (stongest predator other than bear, no way to build anything bear-proof)
Wire needs to be of a minimum of the thickness/gauge of hardware cloth wire, I prefer the 14g wire like rabbit fencing or the goat wire. We use 1/2 ×1" for the bottom 2 feet at least because of our broodies but 1x1 works if you aren't keeping chicks.
As for wire opening dimensions...as stated, smaller is needed for first couple of feet to prevent chicks getting out and average predators from reaching in to grab at birds. Above that the dimensions need to be small enough to prevent entry of the smallest predators in your area. Weasels? Raccoons? Fishers? Some areas will be fine for the average 2x4 goat fencing, if weasels or fishers are in your area you may want to stay with 1x2 wire or chain link.
Remember that most predators are actually very good climbers, even fox if there is any slope on the enclosure. If they can reach it they can use it as an entry. They may be stuck inside then, but by then the damage is done.
Most predators are also good diggers. So a perimeter apron is a good idea. Electricity may provide good perimeter coverage for this.
How wide should my wire apron be? Is folded/double layer chicken wire thick/strong enough to deter digging?
Suggestions for an electric solution that isn't permanent? Hoop coop will be moved several times per week.