How can I effectively increase motion blur past the maximum?

I’d like to create an extreme motion blur, where even the smallest movement is very obviously blurred. I’d like to achieve the effect that every frame was a long exposure photograph. Any ideas on how I can achieve this?

This doesn’t need to happen in real time - I’m saving the frames to disk.

Edit: I tried multiple PostProcessVolume, but that didn’t work.

Have you tried slowing down time? Use set global time dilation and set it to something like .1, I didn’t test it but in theory it should extent the effects or at least pronounce them some