What are some job options for a 20-year-old with no tertiary education?

My 20M partner dropped out of university after struggling with some personal issues, but he has a high school diploma. I know he is capable of working a job, as he has been committed to his part-time job that he has had since he was 15, always showing up and doing the work as needed. However, this job is minimum wage and they refuse to offer him more than part-time, which just isn't enough, as he lives out of home, and needs to pay rent, car fees, daily expenses, etc. He doesn't plan to return to university but is looking for a full-time job. We're both 20, so we don't really know much about career options. What are some options he could look into? He isn't expecting anything amazing, as he knows the most secure jobs are generally obtained by having some sort of degree, but anything helps. Thank you!