A simple Koch Snowflake curve. I had ChatGPT design it in OpenSCAD. Then I stacked them so you can see how each iteration changes. 

Add color changes in your print in order to compare. 

If you want them to tessellate, you will need to scale one by 1/√3, but make sure you only scale the X and Y. The picture of the tiles I made that tessellate is 75% on the smaller ones, and 129.9% on the bigger ones. I used Iteration 4, printed in PLA on my Bambu labs P1S. They tessellate pretty well.