By default, Contact Shadows are disabled on Point Lights, whereby the Point Light's Contact Shadow length is initialized to 0.
To enable Contact Shadows, perform the following steps:
First, drag a Point Light into your scene.
Now, expand the Light section of the Details panel for your newly created Point Light Component by clicking on the expansion arrow.
To enable contact shadows, set the Contact Shadow Length to a value greater than 0.
By setting the Contact Shadow's length to a value greater than 0, you're directing the renderer to trace rays from a pixel's position toward the
light source through the scene's depth buffer. Typically, you'll want to set the Contact Shadow's length to a maximum value of 1, where 1 means
that the ray traverses the entire screen. Whereas, setting the Contact Shadow's length to a value of 0.5 means that the ray traverses
only half of the screen. Note that the number of samples taken in the scene depth buffer remain constant, which means that you'll see more noise
(artifacts) as you increase the Contact Shadow's length. Basically, a Contact Shadow length of 0.75 generates more noise than a length of 0.1.