Destiny 2: Shadowkeep does not require ownership of any previous Destiny 2 expansions to purchase or play.
Something stirs on the surface of our forgotten moon – spiritual remnants of the past, haunted by the memories of their deaths. So strong is their torment that it has begun to reshape reality itself, calling forth waking nightmares that mimic foes once thought conquered by Guardians: warlords, mercenaries, prisoners, and disciples now imbued with dark power, fed by fear itself.