In this case the class teacher of your child is the first contact person. Parents, together with the school should consider which measures are meaningful.
Parents can also contact the counseling centers for gifted education in the school offices in the state of Brandenburg (https://bildungsserver.berlin-brandenburg.de/unterricht/begabtenfoerderung/begabtenfoerderung-bb0/begabtenfoerderung-stuetzpunkte0/).