Is it possible to pay for a car in one day from a dealer and drive it?

Long story short. I live in Bavaria and I will buy my first car in Germany. The cars I am looking for are in Southwest Germany because of less rust.

Now my question is, if I really like the car and decide to buy it on the spot,is it possible to get temporary license plates on the same day and pay for the car? I am not financing it, to the dealer i am a cash buyer. I can make an exception on my online banking to transfer more than my limit once,but I dont know if they wait for the money to be in their account after they give me the invoice? And if such amounts are visible on the same day? 20000€ cca

I then plan to have my license plate ready and my insurance and so on when I arrive in Bavaria with the car.

For temporary license plates I have to buy some separate insurance or not?