1. The map location is shown in the figure below:
2. When you reach the position where you can see the rubbed bark start tracking. See the picture below:
3. After crossing the river, you can see moose droppings. See the picture below:
4. If you follow the railway again, you can find fur. See the picture below:
5. Then you can see the moose. You can also shoot and skin it to get the legendary moose skin. See the picture below:
The above is the entire guide to the location of the legendary moose in Red Dead Redemption 2, I hope it can help you.