Trying to create the amateur trick of a white logo on a black screen that changes to reveal an image through it. Then the logo zooms in to reveal the full image. As one example, this trick is used at the beginning of every Stranger Things episode, as the name of the chapter reveals the scene behind it.
I have two layers, the logo (an AI file) on top and the image below. I set the bottom layer track matte to alpha the one above it and get the look I want, but I actually want the logo to start in white then slowly reveal the image through it. I was thinking that would involve keyframes on opacity, but no, that just makes the logo disappear.
There are a few ways for sure. You might use something like a fill effect to make this bottom layer totally white for example. Then you can access the Compositing Options of the fill effect to apply less of it, similar to how we might fade on the opacity of a layer, but it's the opacity of the effect. I hope that helps get you started in a good direction!