Community expansions for the default maps.
That said, the base game + the free Anniversary Patch + the Steam Workshop offers over 1,000 hours of driving across fictional and real-world routes. If you want the high-quality paid maps like Gladbeck or Ahlheim , your best bet is to wishlist them and wait for a sale. omsi 2 all dlc free upd
While there is no official single "free update" that provides all paid DLC for free, Community expansions for the default maps
Assuming you own the base game and some DLCs, here is how to ensure you have the latest for everything: omsi 2 all dlc free upd