Halo Infinite to Feature the Grappling Hook as Equipment Pick-Up; Arena Will Be About Classic Map Control and Feature a Lot of Power-Ups – Rumor
https://wccftech.com/halo-infinite-grappling-hook-arena/
The rumored Halo Infinite grappling hook is going to be included in the game, but it seems like it won't be one of the main gameplay mechanics.
Speaking on the ResetERA forums, well-known Xbox insider Klobrille revealed that the grappling hook is going to make an appearance in Halo Infinite, but it will be more like the pick-up equipment featured in Halo 3.