There is a plug-in code to get the Max Percent Scrolled, it's called getPercentPageViewed
https://experienceleague.adobe.com/docs/analytics/implementation/vars/plugins/getpercentpageviewed.html?lang=en
Basically, the plugin will track the farthest a person scrolls on a page, then attach the data on the next page view (similar to how Activity Map attaches to the next page).
It actually looks like they added some additional items since I last looked at this.
This solution uses cookies to store the Previous Page Name, the Initial Percent Viewed, the Highest Percent Viewed, the Final Percent Viewed, the Highest Pixel Seen, the Folds Available and the Folds Seen.