numberoptions.scale specifies the size of elements have prior to being revealed.
{ scale: 1 }
The number passed to options.scale is a proportion relative to computed size.
CSS Transforms are preserved. If your element already a scale of 1.5 and you specify options.scale 0.5, your element will initialize with a scale of 0.75 (50% its computed size) and animate back to the computed value of 1.5 when revealed.
ScrollReveal().reveal('.scaleUp', { scale: 0.85 });