In iOS 13, it will be possible to drag the scrollbar to scroll more quickly. This can be done either by long pressing the scrollbar or dragging in from the right at the scrollbar.

A Reddit thread with some info: https://www.reddit.com/r/iOSBeta/comments/bx8nqv/feature_the_scroll_bar_is_grabbable_system_wide/?utm_source=share&utm_medium=ios_app&utm_name=ios_share_flow_optimization&utm_term=enabled