Having up to 10 columns in the related list in Lightning Experience was missing for a long time. As summer'19 is arriving, it has brought this feature with itself. It also allows you to sort, perform mass actions, resize columns and wrap text and show up to 30 records at a time. It is Nothing but Enhanced Related List.

Read more here:-https://salesforcediaries.com/2019/03/26/more-than-four-fields-in-related-list-in-lightning-experience/