Rectangle dimensions in LayOut

Hi, I’m new to LayOut. I want to graph my room for renovations, but I am not able to set the size of the rectangles with scale to my room. Please tell how can I set the dimensions of a rectangle in LayOut 2020.

Have you modeled your room (real size measures) in SketchUp yet?
That is the best route. Then create scenes in SketchUp (‘Parallel’ mode and say ‘Plan’ view etc.)

In LayOut you use these scenes and set the desired scale of SketchUp’s chosen scene.

As @Wo3Dan wrote, the best way to do this is to create your model in SketchUp first and then use LayOut to create your document. That said, it is possible to draw in LayOut to scaled sizes. Look in the Default Tray on the right for Scaled Drawing. Click on the Make Scaled Drawing button, choose the desired scale and proceed to draw with the drawing tools.