https://www.pcgamer.com/destiny-2s-gambit-prime-armor-sets-will-confer-some-pretty-big-bonuses/

One of the biggest things coming in Destiny 2's Season of the Drifter is Gambit Prime. The new mode is an upgraded verson of the PvP/PvE hybrid introduced in Forsaken that, in addition to being played over one round rather than three, will put a greater emphasis on specific roles: Reapers who clear waves of enemies, Invaders who attack opposing teams, Collectors who gather motes and send blockers, and Sentries who defend against opposing Invaders. 

Each class with get its own unique suit of swanky, iridescent armor that looks good and—this is the important bit—confers unique bonuses and abilities. Bungie generally doesn't do set bonuses for armor, and it's not clear whether the bonuses come one-per-piece, or if each additional piece boosts the overall effect. But wearing class-specific armor in Gambit Prime will definitely have an effect.