Shade Sails

You can draw two opposite Edges as lines in top view,
pull one end of each in Z Axis up in an isometric,
use the Loft Tool to create the nonplanar Face between
both lines.

Menu>Model>3D Solids>Loft

That is a simple Shade Sail, with without having its edges bend
also, like in reality.
Maybe it could be created by defining all 4 edges - as Arcs.
But Loft Tool has many options, I would check those in Help System.
I currently also do not see a way how to modify the Loft Object later
but I am sure there are

I'm sure there are other (and better) ways but try this. Make some broad arcs for the edges, ends connecting. Grab them all and convert to a region. Use _dmdeformpoint (Model | Direct Modeling | Deform | Move Point) to grab the center of the region and pull it out or down to form the belly of the sail. Repeat _dmdeformpoint on other points to tweak the shape if desired, say to lift the corners or just to break the symmetry so it looks more natural.