Creating Empty gameobject in Worldspace Canvas, Size problem

I’m trying to create a new object into my Worldspace canvas. The canvas is 2048x2048; the new object is 100x100. Yet the new object appears bigger than the canvas itself in the scene view. How can I do to have a coherent size between element in the same canvas?
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why is the canva’s camera field empty ? assign it your Main Camera then try to use the canvas scaler