If you use a third-party app like Camera+ to shoot RAW, then it is the raw, completely unprocessed sensor data as a DNG file, like any DSLR. Shooting RAW on the ultra-wide camera in a dark environment results in a completely unusable image.
If you use the iOS camera on an iPhone 12 or newer and enable the "ProRAW" option (which is shown as just "RAW" in the camera), you get a processed image, but with the data used as a base for the processing intact for re-processing when you edit it.
If you use the iOS camera on an iPhone 12 or newer and enable the "ProRAW" option (which is shown as just "RAW" in the camera), you get a processed image, but with the data used as a base for the processing intact for re-processing when you edit it.