How do you make time stop automatically at the end? If it's not possible, how do I do it?

There is no automatically end for chapter 1

you can pause the game while opening the case from poppy and stoping the timer at the moment you see one black screen from the end of poppy and chapter 1. I always do it too

okeyy thanks youu

When you submit a run, a verifier will re-time your run for you so you dont need to worry about being exact with the time yourself.