The Offer Details is the data model (XML) that hosts all of the offer and compensation details for a candidate that need to be approved before a recruiting user can present the candidate with an offer. The fields configured in the Offer Details will be used during the Offer Approval (as the information that needs approval) and in the Offer Letter. When building the Offer Details XML, you will reference fields from both the Job Requisition and the Application templates (ex. Job title, location, candidate first and last name, and so on.).
The Offer Details also controls the approval workflow for the offer, as different compensation packages for different levels of positions may require simple or complex approval workflows.
Changes can be down in Offer Approval XML that is downloaded from Provisioning or in Admin Center Manage Template.