Safety and Opportunity for Girls Act of 2023 This bill defines sex under Title IX of the Education Amendments of 1972 as a person's biological sex at birth. (Title IX prohibits discrimination on the basis of sex in federally funded education programs or activities, including in public elementary and secondary schools and in colleges and universities.) The bill also specifies that Title IX does not prohibit schools from having sex-segregated bathrooms, locker rooms, or athletic or academic programs, nor does it authorize the Department of Education to require schools to forgo such sex-segregated facilities or programs in order to receive funding.