with open('huge_csv.csv') as fr:
    with open('huge_output.csv', 'w', newline='') as fw:
        cr = csv.reader(fr)
cw = csv.writer(fw)
cw.writerow(['title1', 'title2', 'title3'])
cw.writerows(cr)
Добавить заголовок в CSV без загрузки CSV