Severance and unemployment, do they overlap? after 18 years as a line cook

I was offered severance of 18 weeks after being let go as a line cook and I am unsure how it affects benefits. I have read a lot of threads here and could not find my exact situation. I also wonder about the job-search requirement. How did your state treat it?

I filed on day one anyway and reported the severance honestly. The agency decided what to do about the timing.