Fortnite has served as a development sandbox for UE4, and in this presentation from GDC 2018 we explore the effort involved with taking FNBR from 30fps to 60fps on consoles and how the game was brought to mobile devices.
https://dev.epicgames.com/community/learning/talks-and-demos/mdj/optimizing-ue4-for-fortnite-battle-royale-gdc-2018-unreal-engine