Harvard does not offer merit-based full scholarships to international students. There is no award you win simply for being the best applicant.
What Harvard College does offer is need-based aid, and it treats international undergraduates the same as American students. If you are admitted and your family has low income, the university can cover your full demonstrated need with grants you do not repay. That can mean paying nothing at all.
The catch is admission itself. Harvard admits only a small share of applicants, and every admitted student is considered for the same need-based aid. Aid follows admission. You cannot apply for aid without being admitted first.
Graduate programs work differently. Each school sets its own fellowships, and most taught master’s programs charge full tuition with limited aid.
So yes, an international undergraduate with full financial need can study at Harvard without paying. But that is need-based aid, not a scholarship prize. Apply through the normal admissions process, submit the financial aid forms on time, and check the numbers with Harvard’s net price calculator.
Related reading: Is Harvard University free for international students?, Can the middle class afford Harvard?, How much does Harvard cost for international students?, and Can I get a full scholarship to Harvard?.

