You probably need to specify these requirements a bit to get better answers (uploading a file helps too). But assuming the rectangles should be circumscribed, a conventional approach is to compute bounding boxes aligned with each edge of the input polygon, and then pick the one with the smallest area. I tried using only components, but snuck a small Python function in there as I couldn’t get the Item Index component to work as (I) expected:
240717_EdgeAlignedBoundingRectangle_00.gh (11.1 KB)
And welcome on board of course 