Shooting in RAW on an iPhone is possible, but it depends on the phone's specific model and operating system version. Some newer iPhone models, such as the iPhone 12 and later, can shoot in RAW built-in to the camera app.
To shoot in RAW on an iPhone, you will need to update to the latest version of iOS, go to your camera settings, and turn on the "Capture outside the frame" feature, which allows you to shoot in Apple ProRAW.
On the other hand, if your iPhone model doesn't have the built-in feature to shoot in RAW, you can use third-party camera apps that allow you to shoot in RAW format. Some examples of these apps include Lightroom, ProCamera, and Manual. These apps will give you more control over your images, such as adjusting the ISO, shutter speed, and white balance.
It's essential to keep in mind that shooting in RAW on an iPhone will result in larger file sizes and will take up more storage space on your phone. Additionally, you will need to use third-party editing software like Adobe Lightroom to convert and process the RAW images before they can be used.
I have an in-depth analysis of the merits of RAW vs. JPG if you want to learn more about the two formats.