Using color adjustment and filters, I've simulated the iOS spotlight animation. Learn how you can apply these filters at https://proto.io/en/new-features/adjustments-filters/
If you need to get the Y position of a vertically scrolling container, create a text box. Then on the container scroll trigger, set a variable that evaluates the numerical callback value from the event (Y position). Then add a callback that changes the text property of the text box by reading from the variable.