What does Render fidelity "Automatic" do

I’ve been wondering for 2 years how does Render fidelity “automatic” affect the 3d model itself? Visually nothing changes, is it just for beauty? Or does it somehow increase performance?

I would recommend checking out its documentation:

“Dynamically control a solid modeled and mesh part’s level of detail depending on its distance from the camera (see table above).”
Well, what does it give then? My 3d model has not changed in any way, how can I feel the difference itself?
Here is “Performance” I see the difference, with the distance the quality of the model is getting worse and worse, and with “precise” on the contrary, but what does “Automatic” I absolutely do not understand