Devices, methods, and graphical user interfaces are used for generating, updating, and / or presenting three-dimensional landscapes in a computer-generated environment. In some examples, an electronic device presents a three-dimensional environment. In some examples, while presenting the three-dimensional environment, the electronic device receives, via one or more input devices, a request to add one or more first two-dimensional objects to the three-dimensional environment. In some examples, in response to receiving the one or more first inputs, the electronic updates an appearance of the three-dimensional environment based on the one or more first two-dimensional objects added to the three-dimensional environment.