General:
* The overarching theme of the conference was sustainability.
* Her overarching goal is to become a doctor.
* The overarching purpose of the project is to improve public health.
More specific:
* The overarching narrative of the novel is about finding one's place in the world.
* The overarching design principle of the building is to create a sense of openness and light.
* The overarching argument of the essay is that social media has a negative impact on mental health.
With an emphasis on scope:
* The overarching impact of the war was felt across the entire country.
* The overarching strategy of the company is to expand into new markets.
* The overarching framework of the government's policies is to reduce poverty.
The key is to use "overarching" to emphasize a broad, overarching idea or goal that encompasses many smaller ideas or goals.