Using Godot 3.2.1 stable.official on Windows 10...
I just added (via cut/paste) your two posted code lines to the _ready()
function of a scene script. Running that scene immediately updates my project.godot
file with the following info:
[rendering]
quality/filters/anisotropic_filter_level=16
Hmmm...
However, when I click back on the Godot editor window (even with the scene still running), that information is immediately removed from the file. Not sure what that means...