Could model one as a mesh, using circles for the corners, or spin tool to get them. Could also use curves to make it and adjust resolution. Third way is to import them from a vector graphics program (.svg), the paths will import as curves.
And since you have CAD background, know that Blender is mainly a polygonal modeling software and polygonal modeling is approximation of curves and surfaces. Fundamentally different from CAD. When using polygonal modeling tools in Blender or in other packages, you’re supposed to use the tools to create a smart approximation, otherwise you’re doing it wrong.
If you’re going to be using Blender I’d suggest getting used to working with meshes. I’d make this by creating a plane and beveling the two vertices with a high segment count and the default 0.5 profile for a round curve.
However, you could use curves and adjust the resolution like JA12 suggested and that offers its own benefits what with the adjustable resolution and you can easily put holes in it by adding circles inside the shape you made if your curve is set to 2D and not 3D. The adjustable resolution is very useful if you ever intend on connecting vertices for cleanly subdividing topology, but that’s not always the goal.
In fact the response will depend of what you want as a result.
I believe if you come from Autocad Rhino, you model from polyline… then extrusion, bolean on solid . … In Blender you will maybe need to think differently… ( i come from Autocad ( 25+ years of professional use and teaching Autocad )
If this is a plane … just create one, and use bevel on the corner ( use mirror modifier as you dont need to create each part separately … )