Hey Fawad, you can use this piece of code to find an element's size using Python Selenium Webdriver:
from selenium import webdriver
from time import sleep
driver = webdriver.Firefox()
driver.get("http://demos.dojotoolkit.org/dijit/tests/test_Menu.html")
timeout = 10
search_element = driver.find_element_by_id("createDestroyButton")
print(search_element.size)
driver.quit()