Getting a second job?

Hi everyone 🙂 I’m 19 years old and I currently work in retail. My job is okay but the only thing that sucks is the hours. I’ll get 8-13 hours a week (it’s been so long that I’ve gotten more than 13 hours) I’ll sometimes be called and asked to work at a different location which is 30 min away from me and I always say yes. The assistant manager told me that the main manager has been trying to cut everyone’s hours which sucks... I’m trying to save up for a car. I’m extremely thankful that I’m able to work during this pandemic going on but I’m thinking of getting a second job because I noticed a lot of places have started hiring again. ( just an fyi, I live in Los Angeles) I’ve never worked 2 jobs so I’m curious on how I should let the manager know or what I should say to him if I do get offered another job? He’s kind of a scary, super serious guy lol so I’m a little nervous. I’m thinking of applying places and seeing how things go. Any advice would be very appreciated!! 🙂