Black and white anime frame

Hi! I was wondering how could I get this effect that can be seen in some animes in which before an explosion or a hit the whole screen goes black and white just to show a flash or some shape of the VFX.

I wanted to know the cleanest or more technically correct way to do this in Unreal.

I leave a couple examples here:
https://x.com/Heavy_2021/status/1537508760712843271?s=20
https://twitter.com/halu_vfx/status/1593199533831647232
https://twitter.com/halu_vfx/status/1608780296337645568
https://twitter.com/halu_vfx/status/1620735117072437250

Thank you!