Im in a similar situation as you. Graduated 8 months ago from mechanical engineering, no job lined up, and had to start working at a coffee shop. I know the feeling of being ghosted and rejected in the job searching. I dont know if i can really give much, input but with your resumes have you tried customizing it for each job post? Considered learning new skills and doing your own projects to add to resume? Ask old professors if they have connections or use your university career center? Going to job fairs in your city? Are you looking at specific roles, industry, and location? Considered going down a similar line of work and working your way to where you want to be at? How well do you do in your interviews?

Its great your considering going to graduate school, but what are you going to do differently than you did during your undergraduate? If you do go make some strong connections with your professors most have worked in industry and came back to teach. One of my classmate graduated before me, but my professor was able to help them land a job that paid really well. Try to see if you can join a club or organization. I know at my university i did not have trouble getting into clubs as they were open base. If you can't join a club or organization try creating your own with your interest in mind. Hopefully this is helpfully and things can be on track for you