Most assets that are used within Unity have been created externally, such as sprites, tilemaps, audio files, models, and so on. There is the possibility to save the source files in the actual Unity file so that whenever updates are made, they are automatically updated within Unity. You can learn more about this in detail by visiting the link the official documentation https://docs.unity3d.com/Manual/ImportingAssets.html or by scanning the QR code: