CREATE TABLE [dbo].[Table1]
(
    [ID] [varchar](50) NULL,
    [DATETIME] [datetime] NULL,
    [Flag] [int] NULL
)

INSERT INTO table1
VALUES ('ID-1', '2019-03-13 09:48:00.000', '2'),
       ('ID-1', '2019-03-13 09:48:00.000', '2'),
       ('ID-1', '2019-03-13 18:11:00.000', '3'),
       ('ID-1', '2019-03-13 18:11:00.000', '3'),
       ('ID-1', '2019-03-14 02:00:00.000', '3'),
       ('ID-1', '2019-03-14 09:54:00.000', '2'),
       ('ID-1', '2019-03-14 09:54:00.000', '2'),
       ('ID-1', '2019-03-14 09:54:00.000', '2'),
       ('ID-1', '2019-03-14 22:00:00.000', '3'),
       ('ID-1', '2019-03-14 22:00:00.000', '3'),
       ('ID-1', '2019-03-14 22:00:00.000', '3'),
       ('ID-1', '2019-03-15 13:55:00.000', '2'),
       ('ID-1', '2019-03-15 13:55:00.000', '2'),
       ('ID-1', '2019-03-15 13:55:00.000', '2'),
       ('ID-1', '2019-03-15 13:55:00.000', '2'),
       ('ID-1', '2019-03-15 13:55:00.000', '2'),
       ('ID-1', '2019-03-15 22:00:00.000', '3'),
       ('ID-1', '2019-03-15 22:00:00.000', '3'),
       ('ID-1', '2019-03-15 22:00:00.000', '3'),
       ('ID-1', '2019-03-15 22:00:00.000', '3')

WITH ins
AS ( SELECT *
     FROM   table1
     WHERE  Flag = 2 )
    ,outs
AS ( SELECT *
     FROM   table1
     WHERE  Flag = 3 )
SELECT   i.ID
        ,i.DATETIME InTime
        ,MIN(o.DATETIME) OutTime
FROM     ins i
         LEFT JOIN outs o ON o.ID = i.ID AND o.DATETIME > i.DATETIME -- out must be later than in
GROUP BY i.ID
        ,i.DATETIME
        ,i.Flag;