The upright posture is very simple. Front view: the aligned body is symmetrical from left to right. Side view: joints are stacked up along the vertical axis.
Better Alignment - Improve Your Pelvic Position
Upright Posture - What Is It? Recognize a proper alignment
How does my posture look - Easy Spine
CHAPTER 4: BODY ALIGNMENT, POSTURE, AND GAIT
Posture: What It Is & Why It Matters for Your Health
Posture Types: Painful Power Leaks You Should Know About
Upright Posture - What Is It? Recognize a proper alignment
Assessment of Posture
How to Set Up an Exercise (or Spin) Bike Properly