AttachUnitySprite
uses SpriteAttachmentLoader
.
SpriteAttachmentLoader
uses the Pixels per Unit setting on your sprite.
But if you want to change it from situation-to-situation:
public Sprite sprite;
[SpineSlot]
public string slotName;
void Start () {
var skeletonRenderer = GetComponent<SkeletonRenderer>();
var regionAttachment = (Spine.RegionAttachment)skeletonRenderer.skeleton.AttachUnitySprite(slotName, sprite);
regionAttachment.scaleX = 3f;
regionAttachment.scaleY = 3f;
regionAttachment.UpdateOffset();
}
If you want to scale that dynamically with animation, you should give that slot a parent bone and animate that scale instead.