Еще один способ, который не требует сортировки или агрегирования.
DECLARE @clientSettings TABLE (ClientId INT IDENTITY, Settings VARCHAR(8000));
INSERT @clientSettings(settings)
VALUES
('{"franchises":[0,7,9,11,14,20,23,26,27,29,33,34,35,45,49,55,57,58,72,73,1,50]}'),
('{"franchises":[1]}'),
('{"franchises":[50]}');
SELECT c.clientId
FROM @clientSettings c
CROSS APPLY
(
SELECT TOP (1) f.franchise
FROM OPENJSON(c.settings, '$.franchises') WITH (franchise INT '$') AS f
WHERE f.franchise IN (1, 50)
) AS x;