Oracle 18c

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CREATE TABLE example (
  effective_date   DATE,
  some_value       NVARCHAR2(32)
);
INSERT INTO example VALUES (DATE '2016-07-01', 'value 1');
1 rows affected

INSERT INTO example VALUES (DATE '2020-08-23', 'value 2');
1 rows affected

INSERT INTO example VALUES (DATE '2021-08-03', 'value 3');
1 rows affected

WITH
  fragmented (
    window_start,
    window_close,
    some_value,
    interval_start,
    interval_close
  )
AS
(
  SELECT
    window_start,
    window_close,
    some_value,
    interval_start,
    CASE
      WHEN add_months(interval_start, 12) < window_close
      THEN add_months(interval_start, 12)
      ELSE window_close
    END
      AS interval_close
  FROM
  (
    SELECT
      effective_date                                        AS window_start,
      LEAD(effective_date) OVER (ORDER BY effective_date)   AS window_close,
      some_value,
      effective_date                                        AS interval_start
    FROM
      example
  )
    lookahead
  
  UNION ALL
  
  SELECT
    window_start,
    window_close,
    some_value,
    add_months(interval_start, 12),
    CASE
      WHEN add_months(interval_start, 24) < window_close
      THEN add_months(interval_start, 24)
      ELSE window_close
    END
  FROM
    fragmented
  WHERE
    interval_close < window_close
)
SELECT
  *
FROM
  fragmented
ORDER BY
  window_start,
  interval_start
;


WINDOW_START
WINDOW_CLOSE
SOME_VALUE
INTERVAL_START
INTERVAL_CLOSE


01-JUL-16
23-AUG-20
value 1
01-JUL-16
01-JUL-17

01-JUL-16
23-AUG-20
value 1
01-JUL-17
01-JUL-18

01-JUL-16
23-AUG-20
value 1
01-JUL-18
01-JUL-19

01-JUL-16
23-AUG-20
value 1
01-JUL-19
01-JUL-20

01-JUL-16
23-AUG-20
value 1
01-JUL-20
23-AUG-20

23-AUG-20
03-AUG-21
value 2
23-AUG-20
03-AUG-21

03-AUG-21
null
value 3
03-AUG-21
null

WINDOW_START	WINDOW_CLOSE	SOME_VALUE	INTERVAL_START	INTERVAL_CLOSE
01-JUL-16	23-AUG-20	value 1	01-JUL-16	01-JUL-17
01-JUL-16	23-AUG-20	value 1	01-JUL-17	01-JUL-18
01-JUL-16	23-AUG-20	value 1	01-JUL-18	01-JUL-19
01-JUL-16	23-AUG-20	value 1	01-JUL-19	01-JUL-20
01-JUL-16	23-AUG-20	value 1	01-JUL-20	23-AUG-20
23-AUG-20	03-AUG-21	value 2	23-AUG-20	03-AUG-21
03-AUG-21	null	value 3	03-AUG-21	null