for the outfit being in the background:
are you talking about mannequins ? if so the link has a template for it/how to do it. but for the mannequins it isn’t tap it and your characters change into it, it’s a choice thing so maybe thats not what your looking for?
for the tapping the outfit, you use tappable overlays. i believe it’s still in beta but it should work.
document on how to use them
and here’s a thread here on the forums explaining them
i think you would save a picture of your outfit and upload it as an overlay then use the tappable overlay code.