Newcomers to Dungeons & Dragons may have difficulty deciphering whether the game is simply a heroic fantasy rule set, or if it takes place in a specific world, but veterans can confirm there is actual canon DnD lore, though it can be ignored. While DnD provides a framework under which a Dungeon Master can create their own homebrew campaign setting, there are also official fantasy worlds published by Wizards of the Coast that form the DnD multiverse. The 5e DnD rules have seen many classic settings return, but often with changes or timeline advancement. The DM and players should discuss how much they want canon to matter in their campaign.
