How to add a scrollbar in qdockwidget in pyqt?

I want to add a scrollbar inside the dockwidget and let it fit the wnd size, and the dockwidget seems re-dock not work.

import sys
from PySide6.QtWidgets import *
from PySide6.QtGui import *
from PySide6.QtCore import *

class My_wgt(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        layout = QVBoxLayout()
        lineedit_list = [QLabel(f"Line {i}") for i in range(30)]

        for i in range(30):
            layout.addWidget(lineedit_list[i])

        self.setLayout(layout)


class My_wnd(QMainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setFixedHeight(500)

        self.dock = QDockWidget("Dock")
        self.dock.setFloating(False)

        self.dock_in_wgt = My_wgt(self.dock)
        self.dock_in_wgt.setFixedWidth(250)

        self.dock.setWidget(self.dock_in_wgt)
        self.dock.setAllowedAreas(Qt.RightDockWidgetArea)
        self.addDockWidget(Qt.RightDockWidgetArea, self.dock)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    main_window = My_wnd()
    main_window.show()
    sys.exit(app.exec())

Heres the code using pyside6, hope somebody can help me. what I want to add

If you want to add a scrollbar to your DockWidget and make it fit the window size, you should place your QVBoxLayout into a QScrollArea instead of directly placing it onto a widget.

import sys
from PySide6.QtWidgets import *
from PySide6.QtCore import *

class My_wgt(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        layout = QVBoxLayout(self)
        scroll_area = QScrollArea(self)
        container = QWidget()
        container_layout = QVBoxLayout()

        lineedit_list = [QLabel(f"Line {i}") for i in range(30)]
        for label in lineedit_list:
            container_layout.addWidget(label)

        container.setLayout(container_layout)
        scroll_area.setWidget(container)
        scroll_area.setWidgetResizable(True)
        layout.addWidget(scroll_area)

class My_wnd(QMainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setFixedHeight(500)

        self.dock = QDockWidget("Dock", self)
        self.dock.setFloating(False)

        self.dock_in_wgt = My_wgt(self.dock)

        sizePolicy = QSizePolicy(QSizePolicy.Preferred, QSizePolicy.Preferred)
        sizePolicy.setHorizontalStretch(1)
        self.dock_in_wgt.setSizePolicy(sizePolicy)

        self.dock.setWidget(self.dock_in_wgt)
        self.dock.setAllowedAreas(Qt.RightDockWidgetArea)
        self.addDockWidget(Qt.RightDockWidgetArea, self.dock)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    main_window = My_wnd()
    main_window.show()
    sys.exit(app.exec())