My iPad can shut down when using it for mapping on my Ranger dash (when 4wd’ing).
I place a cap on it keeping the sun off the body / screen, allowing me to see the screen, works for that and that is in situations of our Australian summer sun / conditions.
For drone flying, I think you’ll have to try a quite broad brimmed hat, like a light cane cowboy style size, put your back to the sun, keep controller / device in shade close to body, seek out a bit of tree shade to stand under the canopy shade, probably a combo of one or more of these.
You might find a sunshade is useful to you anyway, for screen clarity , but as Thomas said, it’s the whole body of the iPad you need to get out of the sun.
Typically those shades are black in colour too, so attract heat !! And quite a lot of it.