Oracle 18c

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CREATE TABLE TABLE1 (ID1   NUMBER
                       GENERATED ALWAYS AS IDENTITY
                       PRIMARY KEY,
                     COL2  NUMBER,
                     COL3  VARCHAR2(20));
CREATE OR REPLACE FUNCTION INSERT_TABLE1(pCOL2  NUMBER, vCOL3 VARCHAR2)
  RETURN NUMBER
AS
  nID  NUMBER;
BEGIN
  INSERT INTO TABLE1(COL2, COL3) VALUES (pCOL2, vCOL3)
    RETURNING ID1 INTO nID;

  RETURN nID;
END INSERT_TABLE1;
/
DECLARE
  nID_value  NUMBER;
BEGIN
  nID_value := INSERT_TABLE1(100, 'First');
  DBMS_OUTPUT.PUT_LINE('nID_value = ' || nID_value);

  nID_value := INSERT_TABLE1(200, 'Second');
  DBMS_OUTPUT.PUT_LINE('nID_value = ' || nID_value);

  nID_value := INSERT_TABLE1(300, 'Third');
  DBMS_OUTPUT.PUT_LINE('nID_value = ' || nID_value);
END;
/
1 rows affected

dbms_output:
nID_value = 1
nID_value = 2
nID_value = 3

SELECT *
  FROM TABLE1;


ID1
COL2
COL3


1
100
First

2
200
Second

3
300
Third