Congratulations on your Model S purchase! I have picked up two from Tesla back in 2019. The procedure is fairly painless, since you'll do most of the paperwork online before you get there and arrange for payment (either in full from your bank, or with a loan). If I remember correctly, we finalized the down payment transfer about an hour or two before I was to pick up the Tesla.
My batteries weren't charged to 90% when I picked up, I'm sure it varies depending on how busy they are. I just drove to the nearest supercharger and topped it off to what was needed.
While you don't get to test drive it before you finish buying it, you should definitely give it a thorough inspection to make sure it is acceptable to you. Most Tesla's won't be perfect, in the way I would expect my $100,000 car to be perfect. Common issues are panel gaps, paint issues, etc. If you find anything that they're willing to fix, I'd make sure to get it in writing on a due bill. Otherwise you also have the option to reject it and wait for another one. But if you don't notice anything out of place, congratulations, you're a new Tesla Owner!