The following are the attributes for the ViewColorManager node. You can access the Attribute Editor for this node by selecting Display > Color Management... from the Render View menu bar.
The Exposure slider is in relative stop values to the original image. Set this attribute to a negative value to darken the image and view details in the over-bright regions of the HDR image. Set this attribute to a positive value to brighten the image and view details in the over-dark regions of the image.