Here’s a fun effect for making clouds seem softer in the sky
The Quick Selection tool usually works well when it comes to selecting sky. Duplicate the background layer and then drag a new selection over the sky.
Once the selection has been made add a layer mask. This mark the sky with white and everything else with black on the mask’s thumbnail.
Click on the layer’s content thumbnail and go to Filter>Noise>Dust & Scratches. Set Radius to 10 and you should see the clouds take on a softer appearance.