In 2.79 and earlier you could alter the size of the sun lamp in order to change the hardness/softness of the shadows. That appears to be gone now, I can’t find any size setting for the sun lamp.
Did you try to change Angle value? You might wanna to.
The new Sum light Angle parameter started life as the “Soft Size” for a Sun lamp in Blender Internal and the default value was 0.1. Cycles inherited this parameter as its “Size”. Neither of these was in a specific physical unit. In 2.80 we now have an explicit angular size in degrees for the apparent size of the sun’s disc in the sky. For new Sun lights in 2.80, the default Angle is something like 0.5 degrees which is physically accurate.
Trivia: The sun and the moon are almost exactly the same size in the sky, equal to about the width of your pinky finger held out at arms length. Believe It Or Not™.
The 2.79 default 0.1 value (which again was in no particular units) gets converted to the large 11.4 degree value when you open a pre-2.80 .blend file in 2.80. It should look the same as it did in 2.79 when you render in Cycles, but it’s not terribly realistic at that size (but gives you nice soft unrealistic shadows).
Ok, thank you very much!