Each country has different rules. The US does not have the concept of “transit passenger” and you will have to enter the US by going through immigration and customs. You may or may not need to go through security again. A couple of hours should be okay.
In Auckland, you do not have to enter NZ (that would currently require quarantine for COVID-19), so your bags may be checked through to Brisbane. In that case you would only need to hang around in the transit area until your next flight leaves.
The best advice is to ask the at the check-in counter when you check in. They will be able to tell you.