Generally speaking, culinary certificates are not required in USA. Health certificates and proof of Sanitation training might be required in some areas or states.
I don't have any cooking certification. Maybe my ten gold medals in American Culinary Federation competition means something to someone but, those mean about the same as a scrap of paper to me. They sure don't prove I can do a produce order or do books! Formal education has it's worth, as a starting point, but most cooking schools do not prepare students for line cooking very well. I left school just before completing the course, because I had a terrific offer from a former employer that really liked me, I guess. No regrets at not having "the paper". I did just fine for 30+ years without one. Still get job offers too. If there is a legal requirement for you to have a certain certification, then you better get certified.
At the buffet place you should be visually interviewing them as well. Every operation has potential as a learning experience. If you like what you are seeing and tasting, stay awhile to learn all you can! I learned a lot, even from the dish room! Keep your eyes and ears open!
Others will give you their opinion and you can ponder your path!
Good luck!