You should be able to achieve that via the “Manage - Manage Configuration - Configuration Report” page. You need to add the following setting:
All Projects, All Users, due_date_update_threshold, integer, 55 All Projects, All Users, due_date_view_threshold, integer, 10
All Projects, All Users, due_date_default, string, today
The 10 and 55 represent viewer and developer. See access levels table for all levels. You can replace with whatever access levels that make sense for your requirement.
See "Columns in View Issues, Csv Export and Excel Export" if you want to add the due_date field to View Issues page.
The default due date can be set to any value like 'today' or '+2 days'. For more details about supported values, see format definition documentation.