Oracle 18c

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CREATE TABLE table_name ( value ) AS
SELECT DATE '2019-11-30' FROM DUAL UNION ALL
SELECT DATE '2021-02-28' + INTERVAL '01:23:45' HOUR TO SECOND FROM DUAL;
2 rows affected

ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS';
SELECT value,
       LEAST(
         ADD_MONTHS( value, 3 ),
         ADD_MONTHS( TRUNC( value, 'MM' ), 3 )
           + ( value - TRUNC( value, 'MM' ) ) DAY TO SECOND
       ) AS value_plus_quarter
FROM   table_name;


VALUE
VALUE_PLUS_QUARTER


2019-11-30 00:00:00
2020-02-29 00:00:00

2021-02-28 01:23:45
2021-05-28 01:23:45

VALUE	VALUE_PLUS_QUARTER
2019-11-30 00:00:00	2020-02-29 00:00:00
2021-02-28 01:23:45	2021-05-28 01:23:45