If you want to use an AI image editing tool to create fantastical scenery, EditApp is worth a look. The tool has three modes: Create, Tweak and Background. The Create mode lets you create fantastical imagery by adding or editing elements like objects, scenes or characters. The Tweak mode lets you edit specific parts of an image, and the Background mode lets you change the environment of an image, a useful way to transport yourself to tropical or extraterrestrial realms.
Another option is getimg.ai, an AI image creation and editing service. It's got a variety of tools to generate original images from text prompts, edit existing images, and train your own custom AI models. With an AI Generator, Real-Time AI Generator and DreamBooth for training your own custom AI models, it can generate high-resolution images and perform image processing. That makes it useful for tasks like creating art and photorealism.