Foreign Service Families Act of 2021 This bill increases access to career and educational opportunities for eligible family members of foreign service employees. Specifically, the Department of State must use additional hiring preferences and apply appropriate hiring standards to eligible family members seeking employment in certain civil service positions overseas. Additionally, the State Department may take other steps to improve job portability and otherwise support employment of eligible family members who work in the federal civil service or private sector jobs. The State Department must also report on the implementation of the Foreign Service Family Reserve Corps, a program that expedites hiring and onboarding processes for family members who are eligible for appointment to positions overseas. Furthermore, each federal agency must include in its telework policy the circumstances under which an employee may temporarily work from an approved location overseas. The bill also makes foreign service employees (or their spouses and dependent children) who are domiciled or assigned to a duty station in a given state eligible for in-state tuition at public institutions of higher education in that state. Such individuals retain their eligibility for in-state tuition provided they maintain continuous enrollment even if their domicile or duty station changes.