I filed my tax return today last day. i haven't got confirmation yet regarding if it is accptd/rjctd as it is pending. should i file an extension, if i dont rcv update?

I filed my tax return today early morning i,e last day. i havent got confirmation yet regarding if it is accepted or rejected as it is pending and will take 24/48 hrs. Now, what if it gets rejected and i didn't get to know untill midnight today (last day), should this be the case where i should file an extension? let me know if i need to file for an extension or not.