Idk how to describe this, you can see difference on the screenshot
Is it possible to make new fog color and density like old one?

The fog responds to your light level and is generally configurable. If you want it to be closer to the old fog, I suggest playing with the fog start height and density options

Nah. Old for more gray than black. It is NOT configurable.
Other settings i configured to parity old fog on the surface at the day, from that moment it is constant and can't be changed