If I get a green card after studying in New Zealand, how can I apply for an Australian green card? I heard that there is a way.

Without this statement, what you may have heard is that after studying in New Zealand for a period of time, you will transfer to Australia to continue your studies and apply for immigration to Australia after graduation. If you already have work experience, you can also apply for Australian immigration directly in the form of skilled immigration. No matter which country you apply for, as long as you meet the conditions, you can apply successfully.