Yes—an iPhone can do it, but you’ll usually need the right app and a very steady setup. Light trails are normally created with a long exposure, or by combining many frames taken in sequence. On an iPhone, that means using an app that can capture repeated shots or simulate a slow shutter effect, then blend them together. A tripod or other solid support is essential so the phone doesn’t move.

Some apps are designed specifically for this and can automate the process on the phone.

A dedicated camera is generally the better option because manual controls make this much easier: you can use a long shutter speed directly and control exposure more precisely. So:

• iPhone: possible with a slow-shutter or frame-stacking app + tripod
• Camera: easier with a model that offers manual exposure and long shutter speeds