Eduardo Pivaral shows off the FOR JSON functionality in SQL Server 2016 and later:
For most of real-world applications, the JSON AUTO will not give you the control you could need over your file format, for having more control over it, you must use the JSON PATH option, along with the ROOT option as follows:
SELECT TOP 10 id, dataVarchar, dataNumeric, dataInt, dataDate FROM [dbo].[MyTestTable] FOR JSON PATH, ROOT('TestTable')
Eduardo has several examples along these lines.