Light Volume is a first-of-its-kind photo effect that lets you create custom light rays with dynamic light sources and interesting texture. Light Volume is a category in the filter chooser of the app, under it you can find the Soft Light and Particulate packs.
Select a filter, position the Light Volume effect off-screen and it will automatically generate a light source out of frame or position the Light Volume effect over your light source in the image and it will automatically detect the bright point.
After positioning and scaling the effect, you have a lot of options to customize the look. Some common adjustments you may want to make are Direction, Threshold, and Brightness. For Particulate filters, dialing in the texture is also really helpful.