I believe what you might want is `get_models()` method on the `Project` class.
Here are the docs (for the latest client version, 3.0.2):
There is an "examples" section in the docs for that method but a very simple version is as follows:
project_id = <YOU_PROJECT_ID>
models = Project.get(project_id).get_models()
And if you want just the model IDs you can use list comprehension in addition to the code above (using `models` variable):
model_ids = [model.id for model in models]
Hopefully that helps and is what you're looking for.