Extension Via online I539 and duration of Stay


New Member
I have filed I539 for my parents for extending there stay in USA as they could not travel back to home country due to Covid. I filed it 45 days before their I 94 expiration (4th Aug 2020). In application I asked for 4 months of extension till Dec 31st 2020. Their application is still pending and it's already been 6 months.
My question is - Does USCIS gives default extension of 6 months via I539 extension or they provide extension as per the time mentioned in application(in my case 31st December 2020)

Please can someone give me clarity on the duration of stay that can be granted to my parents.
I am so confused when to book their return travel tickets and need to take decision asap as airline ticket prices are going high everyday.

Any information will be helpful !!! Please help..