A common way to do this in post is to isolate the bright highlights, blur them, then blend them back over the image.

In Photoshop, one answer suggested:

1. Select the highlights using Select > Color Range > Highlights.
2. Copy that selection to a new layer.
3. Slightly expand the bright areas with Filter > Other > Minimum.
4. Blur that layer with Gaussian Blur.
5. Set the layer blend mode to Screen or Soft Light.
6. Adjust opacity, or duplicate the layer for a stronger glow.

This creates a soft bloom/halation around light sources without affecting the whole image as much.

If you want a similar look in-camera rather than adding it later, a mist filter can create blooming around bright lights while keeping the rest of the image relatively clear. Lighter strengths such as 1/8 or 1/4 are commonly used for a subtle effect; stronger versions produce a much heavier glow.