I can’t find anything concrete, each company does it internally. There are some articles where they publish the starting salary based on your university’s “rank”. Try google translate on this: https://www.google.com/amp/s/www.lexpress.fr/emploi/les-atou...

It discusses how there are 6 ranks for business schools, and your salary for the first N years will be based on that. Same for engineering. It’s funny that one of the companies is proud to declare that they can move salaries by “up to 5%!!!” based on the candidate themselves (whereas the school can make a 20-30% difference...)