What will happen if I do not follow publisher(IEEE/Springer) format for one page? One conference has accepted my paper, but I'm unable to follow publisher format for one page, I have to change some margins for this page.

Actually I've to insert a table and table is slightly bigger in size so I have to change margins and I've tried almost all the possible ways to fit it in that page and I've only one page I can't use more space/page.

If I do this, will they reject my final submitted copy of paper? What will be the effect of this in the printed copy?
It's likely that the typesetter will fix the margins, etc. when it's published. Otherwise, could you slightly reduce the font to make the overall table smaller?