WITH t1 AS
(
SELECT '안녕하세요 데이터 조회 시 조회 된 데이터가 25자 이상인 경우 단어 단위로 줄바꿈 처리 하고 싶습니다.' v
  FROM dual
)
, t2 AS
(
SELECT LEVEL lv
     , REGEXP_SUBSTR(v, '[^ ]+', 1, LEVEL) v
  FROM t1
 CONNECT BY LEVEL <= REGEXP_COUNT(v, '[^ ]+')
)
, t3(lv, v, x, rn) AS
(
SELECT lv
     , v
     , LENGTH(v) x
     , 1 rn
  FROM t2
 WHERE lv = 1
 UNION ALL
SELECT c.lv
     , c.v
     , CASE WHEN LENGTH(c.v) + p.x < 25
            THEN LENGTH(c.v) + p.x + 1
            ELSE LENGTH(c.v)
             END x
     , CASE WHEN LENGTH(c.v) + p.x < 25
            THEN p.rn
            ELSE p.rn + 1
             END rn
  FROM t3 p
     , t2 c
 WHERE c.lv = p.lv + 1
)
SELECT rn
     , LISTAGG(v, ' ') WITHIN GROUP(ORDER BY lv) v
  FROM t3
 GROUP BY rn
 ORDER BY rn
;