Most HS I have seen do not have tryouts for these sports. The sports themselves are the tryout. If you can get through practice, you are on the team. You don't have to be an elite athlete either. Hard work dedication, and sometimes willingness and ability to learn something new. Shot put, discus, javelin, hurdles, and pole vault all tend to have fewer competitors. My family has been solid to strong competitors in these events despite not having great size, strength, or speed.
For other sports, it depends on where you live. Soccer, volleyball, cross country, baseball and softball, tennis, and even basketball can vary greatly in popularity depending on where you live. Look into the less popular sports. They are all fun.