Width for text in a label is in text units. (found http://effbot.org/tkinterbook/label.htm) so what you can do is
def display():
window_width = root.winfo_width() #get current screen width
wrapLen = screen_width/3
tkk.Label(root, text="Some Text", width= ? ,wraplength=wrapLen).grid(column = 0, row=0)
The width can be decided using if statements depending on the screen_width for example it would look like
if window_width == 100:
width = 4.5
elif window_width == 300:
width = 13.5
These are close to the correct values. I calculated with a width of 400 you can get a label width=55 meaning it should be
if screen_width == 400:
width = 18
do these calculations yourself if you please.
SIDE NOTE
also as a side note your doing
from tkinter import *
which imports everything from tkinter. Then importing
from tkinter import ttk
which just reimports the ttk bit.
If I was you I would just do
import tkinter as tk
then everything just becomes
root = tk.Tk()
tk.Label()
tk.Button()
and so on.