Destiny 2 PC will be 'region-locked' according to the region players have set on the BattleNet launcher. The "lock" will default to the BattleNet launcher setting, though players will be able to jump to other regions by selecting them next to the "play" button. Regions include Americas, Europe, and Asia.
Friends wanting to play together will need to make sure their settings are set to the same region as there is no cross-region game play enabled. While friends can be viewed in the list, only those games taking place with the same regional setting can be joined.
Blizzard regions are the player's selected environment through which they are accepting to play with other players. Players may only play with other players who have selected the same region, and cannot join the games or activities of players in other regions. The player's selected region will also limit who appears in-game in a player's Friends Lists and Clan Roster.
When players launch Destiny 2 from the Blizzard desktop application, they will have the option to select their region of play. If the player takes no action to change their region, it will match the default region of the player's Blizzard account.
Players who wish to change their Blizzard region may do so by closing the Destiny 2 application, visiting the Destiny 2 landing page in the Blizzard desktop application, and selecting their desired region from the drop down above "Play".
Source: Destiny 2 Help / Bungie
