Python: if 'X' in 'Y' but with two similar strings as 'X'

[buran]

he only part that wasnt included in the code was that once it found what ending the url had, it would call a function and it would download the file from that url. I needed the ending so I could save it with that specific ending.

That's great example that one should be clear what ultimate goal is.
Instead of checking extensions one by one, you should use proper tools to extract file extension from url

import os
import pathlib

url1 = 'https://www.somedomain.com?download=somefile.div'
url2 = 'https://www.somedomain.com/somefile.divf'

#using os.path.splitext
for url in (url1, url2):
    ext = os.path.splitext(url)[-1]
    local_path = f'c:/somefolder/localfile{ext}'
    print(f'{url} --> {local_path}')
    
print()
# using pathlib
for url in (url1, url2):
    ext = pathlib.Path(url).suffix
    local_path = f'c:/somefolder/localfile{ext}'
    print(f'{url} --> {local_path}')

Output:
https://www.somedomain.com?download=somefile.div --> c:/somefolder/localfile.div
https://www.somedomain.com/somefile.divf --> c:/somefolder/localfile.divf

https://www.somedomain.com?download=somefile.div --> c:/somefolder/localfile.div
https://www.somedomain.com/somefile.divf --> c:/somefolder/localfile.divf
>>>

EDIT: I just realised that you may have a case when it url does not end in desired extension.
In this case you may want to check that extension is in predefined list of "eligible" extemsions.
Also instead of using os and pathlib module you can split url string at '.', take the last element and check if it is in the desired list of extensions.