Universal School Meals Program Act of 2021 This bill revises requirements under the food and nutrition programs of the Department of Agriculture, such as the school lunch and breakfast programs. For example, the bill permanently provides free meals to all school children regardless of income. The bill increases the reimbursement rate for school food authorities participating in the food and nutrition programs. The bill also prohibits school food authorities from (1) physically segregating or otherwise discriminating against any child participating in the free breakfast program, or (2) overtly identifying a child participating in the program with a special token or announcement. Additionally, the bill expands the summer food service program by making all children eligible for participation in the program. Further, the bill revises eligibility determinations for measuring poverty to include runaway or homeless youth, foster children, migratory children, and children participating in specified programs (e.g., Head Start).