The Story Map Swipe and Spyglass template offers the functionality you are looking for: Esri Story Map Swipe and Spyglass - An App for Comparing Maps.
You'd have to create a webmap in ArcGIS Online or Portal for ArcGIS, have 2 feature layers with popups enabled to represent the "before" and "after" states or how you demarcate the change in visualization and feed the Web Map ID into this template.
Here's a popular example that illustrates this: http://storymaps.esri.com/stories/diabetes
Thank you for your response. I do already have many webapps set up using the story map swipe tool. I was looking to be able to use this same functionality within the popup of a layer.
ex. Click on a feature to open a popup, the popup has a image comparison swiper within it.
Thanks for clarifiying that. If you need the swiper within the AGOL popup, i don't think this is a possibility since we do not support embedding <script> tags inside the custom attribute display. One way of workaround is if you could try to host the entire html in a page and embed the iframe or html in the popup.