Take this free packagehttps://assetstore.unity.com/…/fullscreen-cam…/mk-glow-90204
Add MK Glow free controller to ScreenCameraAndInput game object and adjusted parameters.
That's it. But as you understand this is just camera effect. that's mean if you save image it save as normal painting. So if you want to save the glow effect also it required some coding and changing save behavior.