Correct.

请教大家： 我们家现在情况是，大人孩子都是美国绿卡，已经超过5年， 现在大人孩子可以一起申请公民还是大人先申请公民，完成所有程序再帮子女申请？ 

-You need to file N-400 independently. After you become a US citizen, then your minor child (less than 18) will automatically beocme a US citizen. Then, you can file N-600 for your minor child to get the US citizenship certificate or your child can apply for the US passport directly.