Don't just fit a plate over the top, please! It will look like you have done exactly that. It wont look smoothed, it will just look odd with a random plate but still a cut out.
If you have a black car, remove the
badge and colour code it.
If you have any other car, leave it alone.
If you want to get extreme, debadge and smooth the boot properly.
Do it right or don't do it at all, IMO