Is there any option to start an approval process for an attribute modification? We want to trigger it when a manager wants to modify the exit date of a person in the web portal.
There is no ootb option.
But here is a proposal.
In the OnSaving-Script of the Person objects, create a check that reverts the New exit date back to the Old exit date and at the same time, creates a request of a custom multi-requestable resource (QERReuse) that has two request parameters assigned (OldExitDate and NewExitDate). Your OnSaving-code needs to set these parameters in the request as well of course.
That should be it (roughly).