Hold a finger up in front of a torch, and look at the size of the shadow cast. Move the finger closer to the torch, and watch the shadow area increase.
A shadow is always larger than the light-facing area of the object blocking the light. This is true even of your own shadow in sunlight, even though your distance from the light source means the change is so tiny you don't even notice it.
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*drawing not to scaleFor Earth, in solar orbit, that means you'd have to get inside the orbit of Venus.
Then you have a huge energy cost in keeping your shading object in the correct position relative to Earth. Its natural orbit is not going to work at all.
Sol has a diameter of ~100 times the Earth. A shade near Earth would have to be similar size to Earth to block most of the light, and likewise similar size to Sol if it was near Sol.