I agree with the three sided open shed if you’re in Texas. Metal gets HOT and heat will kill a chicken quicker the cold. Build in the shade (if you can) and paint the outsides and roof bright white to reflect the sun. It’s easy to over complicate a chicken coop build, ask me how I know. Chickens basically need safety from predators, nest boxes, chicken feed and water. When you design your build make sure to make it convenient for you too since you will be in and out a lot. If you can build it close to electricity and water access that will make it easier for you. Also, I would design a door wide enough to allow access for a wheelbarrow. For the fencing, use 1/2” hardware cloth and enclose the coop and run entirely with it. Snakes, mice and rats can be a pain in the butt when you’re keeping chickens. One raccoon, possum, mink or stray dog will kill your whole flock. Chicken wire won’t keep predators out, 1/2” hardware cloth will. Burying about a foot of it around the perimeter will keep critters from digging under.
That’s good thinking on your part to over build for more chickens. I was determined to only keep 8 total and I’m up to about 30 now. Good luck with your build!