Curse of Osiris raises the power level cap from 305 to 330, and naturally that means the game's stiffest challenges are being buffed to challenge powered-up players.
Endgame content in Destiny focuses on raids and the Nightfall strike, as well as the more challenging "Prestige" versions of those activities. Destiny 2 has a Gold trophy called "The Prestige" which requires players to "Complete the Leviathan Raid or a Nightfall Strike on Prestige difficulty".
In addition, you'll also need the DLC to access the heroic strike playlist, which returns to Destiny 2 as part of the DLC. With those now being inaccessible to base-game players, so is a platinum trophy. While Destiny 2's PvP mode isn't littered with those making use of the gun right now, as players are still working towards obtaining it, it's only a matter of time before the Crucible becomes overrun with the Exotic.
Since the release of "Curse of Osiris" yesterday, players have found that the Exotic Trace Rifle practically shreds anything in player versus player (PvP) play. With Destiny 2's Power level (the aggregate score of all equipped gear) now jumping up to 330-or 335 with mods attached-from the base game's 300, that means that endgame activities are seeing an increase too.
The expansion also includes Heroic versions of the open-world "Adventures", though on Mercury these still take place inside the instanced Infinite Forest rather than on the planet's surface. It is also available as the first of two planned expansions in the game's $35 expansion pass.