How to create a multiline entry with tkinter?

You could use the Text widget:

from tkinter import *

root = Tk()
text = Text(root)
text.pack()
root.mainloop()

Or with scrolling bars using ScrolledText:

from tkinter import *
from tkinter.scrolledtext import ScrolledText

root = Tk()
ScrolledText(root).pack()
root.mainloop()