Where is the file "Sphinx conf.py" located?

[tyl012]

I am using MyST markdown to write some math notes, and I want to change the configuration. According to the "configuration" part in the documentation

https://myst-parser.readthedocs.io/en/stable/configuration.html#sphinx-config-options

Overriding the default configuration at the global level is achieved by specifying variables in the Sphinx conf.py file. All myst_parser global configuration variables are prefixed with myst_, e.g.

myst_enable_extensions = ["deflist"]

But I cannot find this "Sphinx conf.py". Could anybody please tell me where is it?
Thanks!

[bsipocz]

It usually lives at the root of your docs source directory, there is a vanilla sphinx example at the bottom of the sphinx docs here: https://www.sphinx-doc.org/en/master/usage/configuration.html

[tyl012]

Thank you!