import ctypes as ct 
from tkinter import *

def setWinStyle(root):
    set_window_pos = ct.windll.user32.SetWindowPos
    set_window_long = ct.windll.user32.SetWindowLongPtrW
    get_window_long = ct.windll.user32.GetWindowLongPtrW
    get_parent = ct.windll.user32.GetParent

    # Identifiers
    gwl_style = -16

    ws_minimizebox = 131072
    ws_maximizebox = 65536

    swp_nozorder = 4
    swp_nomove = 2
    swp_nosize = 1
    swp_framechanged = 32

    hwnd = get_parent(root.winfo_id())

    old_style = get_window_long(hwnd, gwl_style) # Get the style

    new_style = old_style & ~ ws_maximizebox & ~ ws_minimizebox # New style, without max/min buttons

    set_window_long(hwnd, gwl_style, new_style) # Apply the new style

    set_window_pos(hwnd, 0, 0, 0, 0, 0, swp_nomove | swp_nosize | swp_nozorder | swp_framechanged)     # Updates

window = Tk()
Button(window, text="button").pack() # add your widgets here.
window.after(10, lambda: setWinStyle(window)) #call to change style after the mainloop started. Directly call setWinStyle will not work.
window.mainloop()