If you are under 18, I think it is a good idea for an adult to accompany you to the job interview .
Of course they will not be allowed into the actualinterview room, but parents can come into the building, meet the job interviewer and at least see where you will work.
When my teenagers looked for their first part time jobs, I went with them. In fact when my 15 year old teenage daughter wanted to work in a local health food store where we shopped, I went with her to pick up the job application and for the interview. She applied to work in the store and at the cash register. However, the day we went for the job interview, we discovered they had a fulfillment warehouse in the basement and that was where she would be employed.
Although a well reputed company, we both became very uncomfortable with the long dark aisles in the storeroom where she would have to pull merchandise. The shelves were easily 8 feet tall which meant she might be on ladders to pull inventory. Additionally, there were a lot of adults working there and so, even though it met the standards set by the Bureau of Labor Statistics, it did not meet mine.
The Hiring Manager saw my discomfort and was anxious to let me know it was a safe environment. My daughter did accept a part time job there.
Adults should accompany teens on their first few part time job searches and help to objectively survey the work environment.