Physician Assistant Higher Education Modernization Act of 2021 This bill assists qualified individuals in receiving the education and training needed to become a physician assistant. Graduate students enrolled in physician assistant education programs are eligible for (1) Direct Subsidized Stafford Loans, and (2) loan forgiveness programs for those who serve in areas of national need upon graduation. The bill also requires the Department of Education to provide historically Black colleges and universities and predominantly Black institutions with grants to fund physician assistant studies at the masters level, prioritize the awarding of grants for physician assistant education programs at the postbaccalaureate level that will benefit Hispanic and low-income students, and allow certain grants to be used to support student matriculation and establish physician assistant education programs at rural-serving institutions of higher education.