Horseman 7: Kill Seven Enemies From Horseback Without Dismounting.
The prerequisite of this challenge is to complete Chapter 1, and the reward is “Horseman Holster Available At Any Trapper”.
In this guide, you will find a way to complete the Horseman 7 challenge in Red Dead Redemption 2.
The easiest way to find seven enemies in the same area is by clearing a gang hideout.
You have to reach the area, start killing enemies, keep moving and use the Dead Eye to avoid your horse taking too much damage.