cat harnesses and a leash (Philadelphia)

Small large and medium. My mom died and now I have our family cat. She was letting him in and out. He has anxiety and is feeling trapped in my apartment. He sits by the door every night and uses every opportunity to get out. If you could please I lost my job in may. He is attacking me because he wants to go outside. He can be very loving but I want him to go outside safely. I want to make sure if I put him in the harness he won't break away. He isn't trained with a harness and I don't know if he will tolerate it. That's why I want different sizes.