Not necessarily. CG boundaries are set for flight. When an aircraft is empty on ground (I mean operating empty, i.e. engine oil, water etc are loaded up, just no fuel and pax) the CG may not be in the middle of the flight boundaries. Not every aircraft is the same, but planes are designed to get the CG in a favourable position when pax, cargo and fuel is getting loaded up. Of course it won’t be completely off when empty, it will still be within the limits, because the plane still needs to be able to fly with only a pilot onboard and minimal fuel.