The cloning layer tool can be used to clone a layer's settings, with or without the feature data included.
This feature is for Admins only.
By going into the Map settings > layer settings, and selecting the ellipses, you can choose how you want to clone your existing layer.
By selecting Clone Layer, it will copy the layer's settings. That includes the layer's styles, its permissions, the events, and the fields associated with that layer. This will not include the layer's features or data. This functionality is helpful for creating a copy of the settings without having to create a layer from scratch.
Selecting Clone Layer + Data will copy over the layer's settings and include the layer's features and data. This will give you a full copy of the original layer plus it's data. This is helpful for when you do not want to edit the original layer and its data.