Google Forms allows users to add a custom header image to their forms, which can be used to match the company's branding and style. This can be achieved by clicking the Customize Theme icon, choosing an image from Google Photos or uploading one, and then editing it to fit within a 4:1 aspect ratio. Users can also customize the color scheme of their form to complement their logo and brand visual identity. Additionally, users can modify font styles and sizes for headers, questions, and text to further enhance their branding.