Answer
No — the underlying database column backing that Description field is defined as NOT NULL at the schema level, which is what makes it mandatory; there's no supported configuration option to relax that constraint or extend its length without an actual code-level customization to the base table definition. Unchecking a custom field's own 'required' checkbox doesn't help, since the original standard Description field's mandatory status is independent of any custom field added alongside it. The practical workaround is to keep the standard Description field as-is (perhaps used only for a short summary) and add a separate custom field to the Change Request header where users can enter the fuller detail they actually need, rather than trying to eliminate or resize the standard field's own requirement.