Whar subjects did you take for IGCSE’s and what 1-9 scores did you get (7+? 6?)
This is important because otherwise you may end up being assignedbto default classes that don’t match your academic background.
Newark’s schools aren’t the best and you’d likely just be assigned to whichever is close to your home.
The only magnets likely to admit junior (rising 11th graders) transfers would be IB diploma schools, since the IB starts in the 11th grade. It’s a highly rigorous program. Look into it immediately since registration may have happened months ago.
Are you a US citizen? Why is your family moving to NJ and to Newark in particular?