Be more specific plz...
Anyway, I make "+" and "-" buttons, conditions, then action would be, set size as width and height, make sure to get expression from sprite.
The sprite is pure square like 100 x 100
Condition
On "+" Pressed
Increasing size:
Sprite1.Width + 20
Sprite1.Height + 20
On "-" Pressed
Decreasing size:
Sprite1.Width - 20
Sprite1.Height - 20