Fields that have been set up as Standard Filter fields or Standard Multiselect Filter fields can be enabled as a search fields on internal and external career sites.
Fields that are enabled on the internal career site does not necessarily have to be enabled on the external career site and vice versa.

User that would like to manage these settings in Admin Center must have relevant permission:
RBP: In Admin Center→Manage Permission Roles→Permission…→select the checkbox for Internal and External Career Search Settings.
Non-RBP: In Admin Center→Manage Recruiting Administration→select the checkbox for Internal and External Career Search Settings.
To enable the field on career site, navigate to Admin Center→Internal and External Career Search Settings. Once you access the page you can decide if you would like to maintain filters on internal or external career site.