Major fallacy in accepted manuscript
The answers are yes and yes. But for most purposes more like yes and unlikely. 

You can ask for time. It may be possible to get time or not. For a conference it is harder, of course, especially when there is some uncertainty about when it will really be finished. For a journal asking for time might cause minor disruption, but it would likely only result in getting published in a later issue of the journal. 

But the editor can also ask that the paper be withdrawn and resubmitted when it is complete. That is up to them. If they thought the paper was originally good, then they are more likely to work with you. 

And be sure to indicate that the paper will be improved, not just corrected.