Starburst

In Lightroom, about all you can do is a Brush to brighten the sun, or draw your own star-streaks with the Brush and increase Exposure of the brushed areas*.

The "sun peeping out" effect is achieved in the camera by using a very small aperture (f16 f22 etc) and only placing the sun part way behind a foreground 'edge' (tree, building, etc). It is the aperture blades in the lens that create the star-streaks.

Photoshop is sure to have a Star-burst filter- but that's another story.

*A technique with the Lr Brush is to- 1) Click with a Large Brush, 2) reduce the Brush size very small, 3) Hold [SHIFT] and Click the brush again in another spot. The effect is this-