Can I pick up the car order at Frankfurt Airport at 10 o'clock if I arrive at 7 o'clock ?

In general, you can pick up the car in advance. I always pick it up an hour or more in advance.

First, you need to see if the car dealership allows you to pick up the car in advance. Second, if you pick up the car in advance, it will be calculated based on 24 hours, and you will also need to return the car in advance.

You can have a try. If the car you book is available, they will provide it for you.

Talk to the car rental company. Generally, if you have a car, you can pick it up in advance, but make sure if you need to return it in advance. In short, ask around to avoid any extra fees later. I have had experiences of picking up a car in advance and returning it in advance without any extra fees.

Can get, I got it at 5 o'clock last time

Try it out instead of waiting