I want a script in PyQGIS 3. For example:

This code creates a layout "2019_A4" and adds Layout Manager. I need a code to make the same in QGIS 3 using the QgsLayoutManager with the duplicateLayout method.

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 = manager.layoutByName("2019_A4")

#layout.initializeDefaults()
#layout.setName('2019_A')
manager.addLayout(layout)