Shooting product photos on a phone: what actually matters
A current phone camera resolves more detail than a listing needs, meters well, and focuses faster than most people can. The reason phone product photos often look worse than camera ones is almost never the sensor.
It is that phones are tuned for photographs of people and places, and a product on a white sweep is neither.
Turn these three things off
HDR. Phone HDR combines several exposures to hold detail in bright and dark areas simultaneously. On a landscape that is a gift. On a product against a white sweep it does the opposite of what you want: it pulls the background down from white towards grey, because a large bright area looks to the algorithm like something to rescue. You then have to push it back up, having lost some product contrast along the way.
Portrait mode. It blurs the background artificially by estimating depth. On a product with a handle, a strap or any gap you can see through, the estimate is wrong at exactly the edges that matter, and the blur is baked in permanently.
Auto white balance, if your camera app allows locking it. Same reason it matters on a real camera: it drifts between shots, so a set of products photographed on one sweep comes out on several different whites.
Most phones expose these in a "Pro" or "Expert" mode. If yours does not, a third-party camera app will.
The five things that actually decide the result
1. Hold it still. A phone braced against something is a different camera from a phone held at arm's length. A tripod with a phone clamp costs about £20 and is the highest-return purchase in this whole article, not for sharpness, but because it fixes your framing so forty products photograph identically.
2. Do not use the ultra-wide lens. Phones have several cameras and switch between them automatically as you move closer. The ultra-wide has the most distortion, and on a product photographed close it bulges the near edge visibly. Step back and use the main camera, then crop. On most phones the main camera is the "1x" setting; check what it switches to when you approach.
3. Step back and zoom slightly rather than moving in. Same distortion issue. A product photographed from 20cm has visibly different proportions from the same product at 60cm. Further back with a modest crop looks more like the object.
4. Tap to set exposure, then check the background. Tapping the product tells the phone to expose for the product, which usually leaves the background dark. Tap the product, then drag the exposure slider up until the background looks near-white but the product is not blown out.
5. Clean the lens. A phone lives in a pocket. A smeared lens produces a soft, low-contrast image that looks like a focus problem and is not. Ten seconds with a cloth before a session.
HEIC and the sideways photo
An iPhone writes HEIC by default, not JPEG. That is generally good, better compression at the same quality, but it introduces the rotation problem where a portrait photograph arrives on its side.
You can set the phone to shoot JPEG instead ("Most Compatible" on iOS), which avoids the whole category. The cost is roughly double the file size for the same picture. If your workflow handles HEIC properly, keep HEIC; if you have ever had a photograph arrive rotated, switch.
What a phone genuinely cannot do
Very shallow depth of field, optically. Portrait mode is a simulation and it fails at complex edges.
Long lens compression. A product photographed at an equivalent 85mm or 105mm looks subtly more solid than one at the phone's roughly 26mm. Cropping in from further away helps but does not fully replicate it.
Tethered shooting into a computer, which for a session of a hundred products is a real workflow advantage.
None of these decide whether a listing sells. Lighting decides that, and lighting costs the same whichever camera you use.
Resolution: you already have enough
A 12-megapixel phone produces roughly 4000 x 3000 pixels. A marketplace main image is commonly 2000 x 2000. That means you can crop away most of the frame and still have more pixels than you need.
Which is a good reason to frame slightly loose and crop afterwards, rather than filling the frame in camera and discovering you clipped a corner.