Create and develop a simple and easy to follow workflow for an ultra-realistic Sci-Fi 3D environment

Please read carefully and thoroughly before bidding or I will ignore your bid. Your bid cost/time is binding. Please provide answers to all questions here: What is the easiest and fastest software(s) to use? What would be the workflow? What is your render engine? The 3D environment is made up using existing assets. No nodes or procedural steps. It has to be created and re-created easily and very quickly whenever needed. It contains colorful floating islands or mountains of shrubs, gardens, with rivers gushing, waterfalls and rivers underneath. Floating fruits. Rivers are not only water but other liquids. The environment is made up of levels. The Ground level fruits trees, Palm trees Sci-fi buildings made of gold. Something like Pandora in Avatar movie. Deliverable: The 3D environment and its working file(s) Easy and simple workflow to build my own in minutes This is a seed project. Please read fully