CREATE TABLE dmo_person ( 
    per_id RAW(16) CONSTRAINT NN_per_id NOT NULL, 
    per_name VARCHAR2(128), 
    per_tags CLOB CONSTRAINT dmo_pers_json_0 CHECK (per_tags IS JSON), 
    CONSTRAINT sko_person_pk_0 PRIMARY KEY (per_id) 
)

insert into dmo_person 
 ( per_id, per_name, per_tags  ) 
values 
 ( 
 sys_guid(), 
 'John Doe', 
 '{ "perm_admin" : 1, "perm_fileuser" : 0, "perm_subcon" : 1} ' 
 )

 DECLARE 
  v_pertags dmo_person.per_tags%TYPE; 
  v_json_obj JSON_OBJECT_T; 
  v_new_pertags dmo_person.per_tags%TYPE; 
BEGIN 
  SELECT per_tags 
  INTO   v_pertags 
  FROM   dmo_person; --where clause 
  v_json_obj := TREAT(json_element_t.PARSE(v_pertags) AS json_object_t); 
  v_json_obj.PUT('perm_bigboss' , 1); 
  v_json_obj.PUT('perm_admin', 0); 
  v_new_pertags := v_json_obj.to_string; 
  UPDATE dmo_person 
  SET    per_tags = v_new_pertags; --where clause 
END; 

select * FROM dmo_person