If someone came to a doctor in the early nineteenth century with blatant symptoms of lung cancer, would it have been recognised and diagnosed?

Probably: "blatant" symptoms would include coughing up blood, difficulty breathing, enlarged lymph nodes, chronic cough, loss of appetite, weight loss, etc. These were recognized signs of either cancer or tuberculosis and early 19th century physicians would have known that. They would not have had the tools to make a diagnosis and of course could not have offered any effective treatment.

Yes but: Such a doctor would likely have suspected infection, such as tuberculosis, much more than lung cancer. Lung cancer was quite a rare disease before the mid-20th century, and people generally didn't live long enough to get it 200 years ago.