The Trustee Scholarship is the largest award USC gives through its Office of Admission, paying full tuition for four years. Around 100 go out each year, selected by USC faculty and staff from a national pool.
USC says plainly that every international applicant who applies by the deadline is eligible for its merit scholarships, and that these awards carry no minimum GPA or test-score bar. Selection looks at the strength of your curriculum, your academic record and evidence of talent, perseverance, innovation, involvement and leadership.
The effort is low, because there is no separate form. The catch is the deadline: apply by 1 November, since a later application removes you from scholarship consideration entirely. It is also tuition only, so you still need to fund housing, food and fees, and USC asks international applicants to document that money at the point of application.