As the largest travel management company, just remember that you make the difference for hotel chains, air carriers, destination management companies, travel agencies, conference and meeting venues... there are a lot of discounts in the travel industry for employees.
How should you prepare for an interview at American Express Global Business Travel?
Make sure you understand the purpose of the open position and check what skills of yours meet their requirements.
Ensure that you have done some investigation about the Company, what it stands for, what type of customers make use of their services.
Be yourself and make sure that what you write on your CV is true and reflecting your capabilities.
Note that interviews are taken in different languages, so if you say you are proficient in a specific language, you will be tested in that language for sure !