How can I edit a photo like this on an iPhone? Is there any apps that can just stack photos together like this?

It looks like 2-3 phots faded onto each other I really want to get this done. https://instagram.com/...ArLB-hlYk/

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Don't know of an app that does it but it shouldn't be too hard to find. I know of a (Windows/macOS) app that can do it, called Picasa & that's a multi-exposure effect. You could probably see if you can find an app that can do that & if not, then use Picasa.