I think bullying behaviour as a way to display power is the result of dark triad personality traits and hubris rather than imposter syndrome.

While insecurity can lead to people being bullies, I think people with imposter syndrome (which by the way, I think is a super over-used term made popular by LinkedIn) are actually genuinely full of self-doubt and lack confidence in their abilities - so I think they’re probably less likely to go on a power trip - because they wouldn’t believe they deserved the power they had in the first place. (If my understanding of imposter syndrome is correct).

These are just my thoughts - I could be wrong.