Change Query Params at Runtime

I am trying to create a system where a pawn runs around randomly within a circle of a given radius. It works fine except for the fact that I have to hard code the Radius for which the pawn will wander. I have included a picture below of the behavior tree. Currently I am using a Query Param to store the Radius (any point outside the radius is filtered).

Is there a way to change Query Params from blueprints or link them to blackboard values? I would like a variable wandering radius.

Thanks for the help.