how do I get a list of emails in line-by-line form?

It is my understanding that apple mail should already be in linear thread. When you open the apple mail app, and click on a email you received recently, it will open the email. If you have already responded to an email, then you should be able to simply scroll up/down in order to see the emails in chronological order from the time you received them as well as showing your responses between each reply that you received. Hope this helps 🧡