How could I control player movement speed while aiming

Hey I am been working on Unreal Engine itself for a while but new to the UNFE. I am trying to create a classic arena shooter gameplay, but could find a way to manipulate player movement speed while aiming.
Is there a way that I can directly manipulate player class? Or is there a ‘device’ I could use to achieve that?

There is a movement_modulator_device device where you can specify effected movement speed. You could create such device on the map and then call Activate/Deactivate on it providing player Agent that you want to affect.