How do I take a single time-lapse photo on iPhone 14 Pro Max?

A single photo cannot be a time lapse photo. A time lapse image is several images over a time period. Once you have the time lapse video, you can save one image from it if that is what you need. Please clarify what you plan to do and we may be able to help you more.

To make a single time lapse photo (not a video) on any camera you need to make an appropriate exposure for the scene you are trying to capture. I'm not familiar with the iPhone 14's camera controls so I can't give you guidance but complete manual control over aperture, shutter speed, ISO, sturdy tripod, and practice are definitely helpful tools to have.

In the meantime while waiting for guidance in this forum I suggest you do an internet search on how it can be done using an iPhone.