How to achieve such a glare effect?

[qggjonny]

This is a screenshot from KeyShot 11 SNEAK PEEK, thanks
https://www.youtube.com/watch?v=MJ7VSe7hs6Y

[Will Gibbons]

It's done in post production. Looks like it was generated in After Effects or similar.

[ivuzem]

I do this in AE. KS has a glow effect, but sometimes it can produce flicker but when it works properly it is actually a nice addition to my AE workflow.
https://www.youtube.com/watch?v=_LlutRBjQOg&ab_channel=GEM-CAD

[sc4r4b]

Make an old school sprite! 

Once you have a glare image/animation apply it to the color and opacity of an emissive material and turn off visible in shadows.  Then apply the newly created glare material to a geometry plane. The glare should be apparent at this point so adjust to your liking. Then move/animate the plane into position in the scene.