Different rules apply to those who are considered a dependent child relying on whether parents are applying for a temporary visa, like a Visitor or Student Visa or a Resident Visa.
#dependentchildvisaNZ
#DependentChildStudentVisa
#ChildVisaNZ
https://nzimmigration.info/residence-visa/child-visa/

The child’s age, parent’s visa type and its conditions will usually determine if you need to apply for a dependent child student visa or visitor visa when applying under the temporary visa category.
#dependentchildvisaNZ
#DependentChildStudentVisa
https://nzimmigration.info/family-visa/dependent-child-visitor-visa/