sample_auto_print_layout_qgis3.py

#from qgis.core import QgsProject,QgsPrintLayout
#https://data.library.virginia.edu/how-to-create-and-export-print-layouts-in-python-for-qgis-3/

import yaml
#envision that this script will use an input yaml file, something like below:
# 
# - map1:
#     data_dir:
#     source_text: |
#       source text line 1
#       source text line 2
#     extent: -12.50, 7.70, -11.30, 9.30
#     basemap: basemap
#     legend: ???
#     legend_placement: [246, 200]
#     layers:
#       - layer1: layer1.qml
#       - layer2: layer2.qml
#     submap: yes
#     submap_extent: [-12.50, 7.70, -11.30, 9.30]
#     submap_basemap: basemap
#     submap_layers:
#       - layer1: layer1.qml
#       - layer2: layer2.qml
#

project = QgsProject.instance()
#get a reference to the layout manager
manager = project.layoutManager()
#make a new print layout object
layout = QgsPrintLayout(project)        
layoutName = "PrintLayout1"

vectorLyr=QgsVectorLayer("insert file path","RoadLayer", "ogr")
project.addMapLayer(vectorLyr)


layouts_list = manager.printLayouts()

for layout in layouts_list:
    if layout.name() == layoutName:
        manager.removeLayout(layout)

#initializes default settings for blank print layout canvas
layout.initializeDefaults()  
layout.setName(layoutName)
#add layout to manager
manager.addLayout(layout)

map = QgsLayoutItemMap(layout)

# Map
#   Defaults of `A4` (210 x 297 mm), `Landscape`, & `LayoutMillimeters` are 
#   due to `layout.initializeDefaults()`
map.setRect(250, 250, 250, 250)                                     

#Set Map Extent
#defines map extent using map coordinates
#QgsRectangle(xMin: float, yMin: float = 0, xMax: float = 0, yMax: float = 0) 
rectangle = QgsRectangle(-12.50, 7.70, -11.30, 9.30)
map.setExtent(rectangle)

#map.setExtent(iface.mapCanvas().extent())

#add the map to the layout
layout.addLayoutItem(map)

#Move & Resize map on print layout canvas
map.attemptMove(QgsLayoutPoint(5, 5, QgsUnitTypes.LayoutMillimeters))
map.attemptResize(QgsLayoutSize(287, 200, QgsUnitTypes.LayoutMillimeters))


minimap = QgsLayoutItemMap(layout)

minimap.setRect(250, 250, 250, 250)                                     

rectangle = QgsRectangle(-13.50, 6.70, -9.90, 10.30)
minimap.setExtent(rectangle)

layout.addLayoutItem(minimap)

minimap.attemptMove(QgsLayoutPoint(212, 5, QgsUnitTypes.LayoutMillimeters))
minimap.attemptResize(QgsLayoutSize(80, 60, QgsUnitTypes.LayoutMillimeters))


#Checks layer tree objects and stores them in a list. This includes csv tables
checked_layers = [layer.name() for layer in QgsProject().instance().layerTreeRoot().children() if layer.isVisible()]
print(f"Adding {checked_layers} to legend." )
#get map layer objects of checked layers by matching their names and store those in a list
layersToAdd = [layer for layer in QgsProject().instance().mapLayers().values() if layer.name() in checked_layers]


legend = QgsLayoutItemLegend(layout)
legend.setTitle("Legend")
root = QgsLayerTree()
for layer in layersToAdd:
    #add layer objects to the layer tree
    root.addLayer(layer)
legend.model().setRootGroup(root)
layout.addLayoutItem(legend)
legend.attemptMove(QgsLayoutPoint(246, 200, QgsUnitTypes.LayoutMillimeters))


"""This adds labels to the map"""
title = QgsLayoutItemLabel(layout)
title.setText("Title Here")
title.setFont(QFont("Arial", 28))
title.adjustSizeToText()
layout.addLayoutItem(title)
title.attemptMove(QgsLayoutPoint(10, 4, QgsUnitTypes.LayoutMillimeters))

subtitle = QgsLayoutItemLabel(layout)
subtitle.setText("Subtitle Here")
subtitle.setFont(QFont("Arial", 17))
subtitle.adjustSizeToText()
layout.addLayoutItem(subtitle)
subtitle.attemptMove(QgsLayoutPoint(11, 20, QgsUnitTypes.LayoutMillimeters))   #allows moving text box