I want script in python3 with QGIS 3?

For example:

This code create a layout **2019_A4** and add Layout Manager. I need a code make same in QGIS3 using **QgsLayoutManager** with Methods **duplicateLayout**

Here: https://qgis.org/pyqgis/3.4/core/QgsLayoutManager.html

    from qgis.PyQt.QtCore import *
    from qgis.core import *

    # A Project, Manager, & PrintLayout Classes
    project = QgsProject.instance()
    manager = project.layoutManager()
    layout = QgsPrintLayout(project)
    layout.initializeDefaults()
    layout.setName('2019_A')
    manager.addLayout(layout)