If you're looking for a tool that lets you try out different design styles and generate lots of variations, Recraft could be a good choice. It's a generative AI design tool that lets you create and edit digital illustrations, art and 3D graphics in a consistent brand style. Recraft has features like image stylization, iterative design, style remixing and an AI upscaler for larger images. It also has a free version with most of its abilities, so you can start experimenting right away.
Another good option is Uizard, an AI-based UI design tool that lets you quickly create and experiment with product designs. Uizard has tools like a text-to-UI generator, drag-and-drop editor and real-time collaboration abilities. Its AI abilities include the ability to generate designs from screenshots and predict where users will focus, so it's good for mobile and web app designs.
If you're looking for a broader set of creative tools, check out Runway. The platform offers Text to Image, Image to Image and other generative tools to help you quickly explore and iterate on ideas. Runway is used by professional creatives in film, advertising and education, and it offers a variety of plans to match your needs, including a free plan with limited credits.