Yes, there are several AI tools that can help you resize images for T-shirts or any other merchandise. One popular tool is called "Waifu2x," which was originally designed to upscale anime-style images but can work well for other types of designs too. Another option is Adobe Photoshop's "Content-Aware Scale" feature, which can intelligently resize images while preserving important details. Additionally, you can explore online services like Canva or Pixlr, which offer resizing and editing features tailored for graphic design purposes. Make sure to review the terms of service and any usage restrictions when using these tools for commercial purposes like selling on Amazon merch.