This is the documentation for Enlighten.

Real-world sun/sky intensity

To simulate real-world intensity of sunlight, set the Directional Light intensity to around 2000. 

For D3D11, D3D12, PS4, Xbox One and Switch, this produces good results with Enlighten.

For other platforms, in a level with a directional light with an Intensity of above 16, or a sky light with Intensity above 1000, you may notice darker-than-expected indirect lighting with Enlighten lightmaps. This is because Enlighten lightmaps use a fixed-point HDR representation on these platforms.

In this scenario, Enlighten indirect lighting looks dark and flat. To prevent the issue on these platforms, we recommend limiting the intensity of the directional light to a maximum of 10.