Can the Nikon D850 focus with ease in low light conditions?

I currently own a D3200 which has difficulty focusing in low light conditions, and I'm thinking of upgrading to a semi professional camera.

Added (1). Does The Nikon D850 have improved auto focus in low light conditions compared to the Nikon D810?

No matter how good an AF system is, when light is very low, it will fail. That is unless you're using infrared.

The D850 has no low light focus assist lamp. To use a feature like that, you will need a Nikon flash that has its own focus assist beam.