how to check nls format in oracle

1SELECT *
2FROM (SELECT 'SESSION' SCOPE, nsp.* FROM NLS_SESSION_PARAMETERS nsp
3      UNION ALL
4      SELECT 'DATABASE' SCOPE, ndp.* FROM NLS_DATABASE_PARAMETERS ndp
5      UNION ALL
6      SELECT 'INSTANCE' SCOPE, nip.* FROM NLS_INSTANCE_PARAMETERS nip) a
7PIVOT (listagg(VALUE) WITHIN GROUP (ORDER BY SCOPE) FOR SCOPE IN (
8    'SESSION' AS "SESSION" ,'DATABASE' AS DATABASE ,'INSTANCE' AS INSTANCE));
9-- ⇓ Test it ⇓ (Fiddle source link)