Object created with lines to rectangle.

Hi guys,

can you help me please? A want set object created with lines like rectangle. (polygon)
Is the way how i can do it?

Add a one-step Contour to the small rectangles.

Arrange > Convert to Editable Shapes > Ungroup

Make sure the outer ring of the small rectangles overlaps the large rectangle

Select one of the rings and the large rectangle. Arrange > Combine Shapes > Subtract Shapes.