Yes, metal utensils can scratch a cast iron skillet. Cast iron skillets have a durable surface, but they are not immune to scratches, especially when using metal utensils with sharp edges or rough surfaces. Scratches on the seasoning (the layer of polymerized oil that creates the non-stick surface) can lead to food sticking and make the skillet more challenging to clean and maintain.
To preserve the seasoning and prevent scratches, it's best to use utensils made of softer materials like wood, silicone, or nylon when cooking with a cast iron skillet. These materials are less likely to damage the surface of the skillet. If you do accidentally create some scratches, don't worry; it's a normal part of the skillet's life, and you can always reseason it to restore its non-stick properties.
Remember, proper care and maintenance of your cast iron skillet, including using the right utensils, will help it last for generations.