This Seeking Tech tutorial will show you how to acquire The Early End trophy and achievement in Metal Gear Solid Delta: Snake Eater.
For this to unlock, you need to “kill The End before the boss battle.”
When you first enter Ponizovje South, go to the northwest exit to enter Ponizovje West. From there, you should find the SVD sniper rifle in the small warehouse building.
Once you find the weapon, equip it and familiarize yourself with its controls and handling.
Afterwards, exit back to Ponizovje South and then head to the northern exit to Ponizovje Warehouse: Exterior.
Once the cutscene ends, quickly use your SVD to shoot at The End before he gets pushed away. If you mess up, immediately reload the auto save file and try again.
You can check out the video walkthrough below if you need a visual aide: