Launch providers list the characteristics of their vehicle and the customer has to ensure to stay within the constraints.

SpaceX is special (or used to be special, maybe others have followed suit by now?) in that they make this information public. See here what loads, accelerations or vibrations the payload has to withstand during a launch on a Falcon 9 or Falcon Heavy launch vehicle:

https://www.spacex.com/media/Falcon_Users_Guide_082020.pdf#p...