LinearLayoutManager subclass that "peeks", shows a portion of the adjacent child views.

PeekingLinearLayoutManager.kt

class PeekingLinearLayoutManager : LinearLayoutManager {
    @Suppress("Unused")
    @JvmOverloads
    constructor(context: Context?, @RecyclerView.Orientation orientation: Int = RecyclerView.VERTICAL, reverseLayout: Boolean = false) : super(context, orientation, reverseLayout)

    @Suppress("Unused")
    constructor(context: Context, attrs: AttributeSet, defStyleAttr: Int, defStyleRes: Int) : super(context, attrs, defStyleAttr, defStyleRes)

    override fun generateDefaultLayoutParams() =
            scaledLayoutParams(super.generateDefaultLayoutParams())

    override fun generateLayoutParams(lp: ViewGroup.LayoutParams?) =
            scaledLayoutParams(super.generateLayoutParams(lp))

    override fun generateLayoutParams(c: Context?, attrs: AttributeSet?) =
            scaledLayoutParams(super.generateLayoutParams(c, attrs))

    private fun scaledLayoutParams(layoutParams: RecyclerView.LayoutParams) =
            layoutParams.apply {
                when(orientation) {
                    HORIZONTAL -> width = (horizontalSpace * ratio).toInt()
                    VERTICAL -> height = (verticalSpace * ratio).toInt()
                }
            }

    private val horizontalSpace get() = width - paddingStart - paddingEnd

    private val verticalSpace get() = height - paddingTop - paddingBottom

    private val ratio = 0.9f
}

You might want to add the following change to avoid showing an empty space when there is a single item:

 private fun scaledLayoutParams(layoutParams: RecyclerView.LayoutParams): RecyclerView.LayoutParams {
        if (itemCount == 1) {
            return layoutParams
        }

        return layoutParams.apply {
            when (orientation) {
                HORIZONTAL -> width = (horizontalSpace * ratio).toInt()
                VERTICAL -> height = (verticalSpace * ratio).toInt()
            }
        }
    }

It is not working when we have item height more than item width