You asked
What lenses should I buy for the nikon z8?
If you don't tell me what you shoot, I'd start with a simple everyday kit for the Z8. Get the Nikon Z 24-70mm f/2.8 S II as your main zoom. It covers most of what you'll photograph day to day.
For reach, the Nikon Z 70-200mm f/2.8 VR S II is the one to add for sport, wildlife, or portraits from a distance.
For a small, cheap step into primes, try the Nikon Z 50mm f/1.8 S. Since you'll be buying into the Nikon Z mount for years, it's worth checking the three questions on the home page before you commit.
Written by Claude from this site's pages.