SQL Server 2022

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create table myTable (id int, amount int, [Order] int);
insert into myTable (id, amount, [Order]) VALUES 
 (1,       100,       1),
 (1,       300,       2),
 (1,       320,       3),
 (2,       100,       1),
 (2,       200,       2),
 (2,       423,       3),
 (2,       613,       4),
 (3,       112,       1),
 (3,       218,       2),
 (3,       290,       3),
 (3,       480,       4);

select t1.*, case when t2.id is not null then 'Y' else '' end as FLAG
  from myTable t1
  left join (
select id, min([Order]) minOrder
  from myTable
  where ( [Order] >= 3 and Amount >= 400)
  group by id) t2 on t1.id = t2.id and t1.[Order] = t2.[minOrder];

SELECT ID, AMOUNT, [Order],
       CASE WHEN [Order] >= 3 AND AMOUNT > 400 AND
            NOT EXISTS (
                SELECT 1
                FROM myTable t2
                WHERE t2.ID = t1.ID AND
                      t2.[Order] < t1.[Order] AND
                      t2.AMOUNT > 400
            )
            THEN 'Y' END AS Flag
FROM myTable t1
ORDER BY ID, [Order];

id	amount	Order	FLAG
1	100	1
1	300	2
1	320	3
2	100	1
2	200	2
2	423	3	Y
2	613	4
3	112	1
3	218	2
3	290	3
3	480	4	Y

ID	AMOUNT	Order	Flag
1	100	1	null
1	300	2	null
1	320	3	null
2	100	1	null
2	200	2	null
2	423	3	Y
2	613	4	null
3	112	1	null
3	218	2	null
3	290	3	null
3	480	4	Y