The 'user.cfg' file enables all 70 hidden Diary Pages + 21 Post Cards. Once you have downloaded the files and pasted on the save folder, start the game and simply head to 'New Game', select 'Slot #1', press 'New Game Plus', next 'My weapons' and enjoy. On XboxOne/PS4 you can have the weapon as well but any attachments will not be available as they were put in the DLC only.
With this update/dlc it provides a full weapon usage, not only for the DLC but for the single-player immersion through in-game Developer Console and for that it can only be done for PC version. With recent Summer Update and the release of the first DLC 'The Two Colonels' [4A Games completed the cut flamethrower which can be found in the game, hidden in certain areas out of boundaries. It also features a full customizable flamethrower weapon. This save allows you to start a NewGamePlus with all content being unlocked.
Since 4A Games released the Ranger Update [with the ability to start the game with our own gear after game completion.
You can now jump from map-to-map with all weaponry, here is the guide at Metro Exodus - Developer Console Thanks to SunBeam, we can now use the Developer Console and NoClip features. ⛔️ Unfortunately it is NOT possible to use Sam's Story DLC content carried over Artyom's journey due to game engine mechanics being different from normal content and DLC content ⛔️