How to build a header parallax correctly with Custom UICollectionViewLayout

Question

I want to build a top parallax that the image grows as you go down with the scroll collectionView of the screen.

I'm using a CustomLayoutAttributes to get the attribute and increase it.

Example:

private func updateCells(_ attributes: CustomLayoutAttributes,
                     halfHeight: CGFloat,
                     halfCellHeight: CGFloat) {


  let cellDistanceFromCenter = attributes.center.y - contentOffset.y - halfHeight
  let parallaxOffset = -(settings.maxParallaxOffset * cellDistanceFromCenter)
 (halfHeight + halfCellHeight)

  let boundedParallaxOffset = min(
      max(-settings.maxParallaxOffset, parallaxOffset),
      settings.maxParallaxOffset)

  attributes.parallax = CGAffineTransform(translationX: 0, y: 
   boundedParallaxOffset)

In addition to that, you have few subviews on the cell. My problem is, every time I increase the cell the subviews grow up with the cell.

How do I make the cell grow but the subviews inside not grow???

This is a reference to a project:

https://www.raywenderlich.com/527-custom-uicollectionviewlayout-tutorial-with-parallax

Thanks