По ссылке В.Бокшича я сделал этот запрос в качестве ответа:
DECLARE @json NVARCHAR(MAX)
SET @json = (SELECT (JSON_QUERY((
SELECT 'Ball' AS title,
'Blue' AS color, (
SELECT '1' AS Opt1,
'2' AS Opt2
FOR JSON PATH
) AS Options
FOR JSON PATH, WITHOUT_ARRAY_WRAPPER
))) AS product
FOR JSON PATH, WITHOUT_ARRAY_WRAPPER)
SELECT @json
Вывод:
{"product":{"title":"Ball","color":"Blue","Options":[{"Opt1":"1","Opt2":"2"}]}}