Reach weapons helps with that.
Also, even though in vanilla 5e Enlarge Person doesn't increase reach of the target - it's surely one of things that worth changing.
Maybe even bringing higher-level option, with target growing to huge size (similar to how it's done in Pathfinder 2e). With those changes, huge party member with reach-weapon would have 20ft. reach, or 15ft. with regular weapons.
