Grace Period is defined on the Utilty object and record type : One Quote Grace Period

It can be found on the filter name : Grace Period.

Only Users with the Permission set : "Data Manager" can creat or edit these records.

At Quote Creation (from Account, Scratch, Cloning , reneweing) a Grace period record is defined based on the One Quote GBU, BU, Region , Account Customer Segment.

It prefill the value Quote Valid to to the "Default External Validity"

It prefill the value Quote Valid From  to the "Price Valid to Internal"

A validation rule prevent users to set a  Quote valid to and from when the number of days inbetween is above the "Max External Validity"