Ok try this.
Create a fresh Actor
Call it BP_Grow
Add Box collision
Untick Hidden in Game so you can see box in gameplay
Make the box bigger
Add this to event graph
VERY IMPORTANT - In the timeline make sure the starting value is 1 for all vectors at time 0 as this is the default mesh size. Change the end value to how much you want to grow by like 2.
For Shrink do the exact same except use this timeline, end value how much you want to shrink by like 0.5.
