Image source:

Symbol 1, https://tex.stackexchange.com/questions/404925/animated-koch-snowflake/404935

Live example

https://openprocessing.org/sketch/1465346

Editable code

p5.js Web Editor

Learning resources

8.3: Fractal Recursion with ArrayList of Objects (Koch Curve) - The Nature of Code

Shader Coding: KIFS Fractals explained!

Chapter 8.4 The Koch Curve and the ArrayList Technique:

The Nature of Code