example of changing currently displayed widgets/layout in PyQt6 using QStackedWidget

stacked_widget_example.py

import sys

from PyQt6.QtWidgets import (
    QApplication,
    QCheckBox,
    QLabel,
    QLineEdit,
    QRadioButton, )
from PyQt6.QtWidgets import QHBoxLayout, QFormLayout, QStackedWidget, QListWidget, QWidget


class StackedExample(QWidget):

    def __init__(self):
        super().__init__()
        self.left_list = QListWidget()

        self.setWindowTitle('StackedWidget demo')

        self.left_list.insertItem(0, 'Contact')
        self.left_list.insertItem(1, 'Personal')
        self.left_list.insertItem(2, 'Educational')

        self.stack = QStackedWidget(self)
        self.left_list.currentRowChanged.connect(self.stack.setCurrentIndex)

        self.name_address_form_stack = QWidget()
        layout = QFormLayout()
        layout.addRow("Name", QLineEdit())
        layout.addRow("Address", QLineEdit())
        self.name_address_form_stack.setLayout(layout)

        self.biographical_information_stack = QWidget()
        layout1 = QFormLayout()
        sex = QHBoxLayout()
        sex.addWidget(QRadioButton("Male"))
        sex.addWidget(QRadioButton("Female"))
        layout1.addRow(QLabel("Sex"), sex)
        layout1.addRow("Date of Birth", QLineEdit())
        self.biographical_information_stack.setLayout(layout1)

        self.academic_subjects_stack = QWidget()
        layout2 = QHBoxLayout()
        layout2.addWidget(QLabel("Subjects"))
        layout2.addWidget(QCheckBox("Physics"))
        layout2.addWidget(QCheckBox("Math"))
        self.academic_subjects_stack.setLayout(layout2)

        self.stack.addWidget(self.name_address_form_stack)
        self.stack.addWidget(self.biographical_information_stack)
        self.stack.addWidget(self.academic_subjects_stack)

        hbox = QHBoxLayout(self)
        hbox.addWidget(self.left_list)
        hbox.addWidget(self.stack)
        self.setLayout(hbox)

        self.show()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = StackedExample()
    sys.exit(app.exec())