Most likely it was a combination of the phone focusing at its minimum distance, digital zoom/cropping, and possibly flash or stronger light.

A phone camera can only focus so close. If your later attempts were slightly inside that minimum focus distance, the image would look much softer. The detailed shot may also have used digital zoom or a crop, which makes the texture appear more “macro” even though the lens itself is not a true macro lens.

Flash or brighter light can also help by increasing contrast and allowing a faster shutter speed, which makes fabric fibers look crisper.

Another possibility is that something like a tiny water droplet on the lens briefly acted like a makeshift macro attachment, letting the camera focus much closer than normal. That can happen accidentally in humid or wet conditions.

To try to repeat it: use the brightest light you can, enable flash if needed, use some digital zoom, and carefully move the phone back and forth until focus locks at the closest sharp point. If your camera app allows manual focus, set it to the closest focus distance.