I show all endings in one playthrough in my Achievement Walkthrough with Commentary using a very easy load last checkpoint method.
Choices to make at the end of Chapter 5: Acceptance.
Unplug Ewa, Stay in the Bunker, QUICKLY reload last checkpoint after getting the two Achievements.
This time choose, Don't Unplug Ewa, Leave the bunker, let the game end and the achievement for seeing all endings will unlock during the final cutscene/credits.
Skip to 1:13:01 minutes into the video to see this method.
0:10 Chapter 1
10:03 Chapter 1 Untermensch
14:23 Chapter 2
33:09 Chapter 3
50:14 Chapter 4
1:09:37 Chapter 5
1:16:11 Achievements: Sleep Sister, Beacon of Hope
1:17:05 Achievements: I can’t do it, Don’t look back
1:20:00 Chapter 1 Übermensch