How to add Floating Island Geometry Node to your Object.

Select Your Object > Navigate to Modifier Properties > Add Modifier > Select Geometry Nodes.

--Note: When creating the shape for the floating island, compare the ruler size with the HumanRealscale object to achieve the best results.

And don't forget to Apply -> Rotation & Scale to reset the Object's parameters.

How to Modify Materials for Your Island Elements.

Select the Element Collection you want to modify. > Select Object > Navigate to Material Properties. 

You can also add your own objects to the collectionto enhance the variety of the floating island. Just ensure that the size of the object is appropriate and Apply -> Rotation & Scale to reset the Object's parameters.

Cliff_Material Name.