use dataclasses for configs

[elray1]

define base_config as a dataclass and then instantiate it with model_name, p, power_transform, etc. as needed

[elray1]

One pattern is to replace your base config with a dataclass:
In [8]: @DataClass
...: class ModelConfig:
...: sources: list[str]
...: model_name: str = "sarix"
...: fit_locations_separately: bool = False
...: # model parameters
...: p: int = 1
...: P: 0 = 0
...: #etc
...: power_transform: str = None
And create a helper function that returns a ModelConfig instance based on passed parameters:
In [9]: def get_model_config(sources: list[str], fit_locations_separately: bool, p:int) -> ModelConf
...: ig:
...: model_config = ModelConfig(sources=sources, fit_locations_separately=fit_locations_separ
...: ately, p=p)
...: return model_config
And then in the code that parses args:
mc = get_model_config(["hhs"], fit_locations_separately=True, p=5)
The dataclass attributes work in the same tidy way as the SimpleNamespace
In [11]: mc
Out[11]: ModelConfig(sources=['hhs'], model_name='sarix', fit_locations_separately=True, p=5, P=0, power_transform=None)

In [12]: mc.model_name
Out[12]: 'sarix'