I guess you’re thinking of something that orbits earth? If you build something that orbits the sun at the same rate as us then it could just be flat and circular.

Maybe someone smarter than me can calculate the optimal parameters to get the smallest shade that orbits the sun. If we are looking to only block out a percentage of the sun then it doesn’t even need to be fully opaque, maybe a giant dream catcher would be fine.

Shades could just orbit like any other artificial satellite. It does not have to block the sun all of the time, just part of the day.

I suspect the atmosphere, ecology and albedo would adjust to radiate the extra energy away anyway.