The extension filed on 3.15.20 would have given until 9.15.20 to file the return. 

The 3.15 filing date was NOT automatically extended by the same actions taken to give individuals until 7.15. - as that pronouncement came out subsequent the the 3.15 due date for S-Corps & Partnerships.

The S-corp due date was 3/15, if you didn't extend or file on or before that date, youre late ...you can't file any extensions now.

It was 3/21 they decided to extend the due date for returns until 7/15....the S-Corp due date had already passed by that time and would have been taken care of one way or the other prior to 3/21.