From Trend Patterns:
The Trench Jacket has been designed by taking inspiration from the catwalks trends seen in New York, London, Milan and Paris fashion weeks. This design is inspired by the Utility trend seen everywhere, combined with an oversized silhouette.
This pattern is best made with a heavy to medium weight fabric such as cotton drill as seen in the images below. Alternatively, this jacket would look great made in denim or similar.
Variations
The front jacket edge has a concealed button placket to fasten the jacket. However this can be ignored and the belt can be used as an alternative closure.
The vent can also be ignored and the center back closed to the hem if you do not want to construct it.
The large pocket bag can also be ignored as seen in images below.
Difficulty - Easy-Hard.
Depending on the amount of details you choose to include in your jacket, the difficulty level will differ. There are a few suggestions above to simplify.