Sciatic type pain down one or both legs and numbness in feet 4 years after t12 fracture. Could they be connected? Thank you

Could be. A severe t12 fracture could create pressure or damage to the nerve roots or even spinal cord, and create numbness into legs. Would expect that to come on right after fracture. Changes in ligaments and tissue around spine in time after fracture could also give radiating pain. Depends on the timing and severity of fracture. Worth seeing a physiatrist.
No. The t12 dermatome or nerve motor function is for abdominal muscles and intercostals or ribs.
Neuropathy or nerve pain in the feet would not be due to t12 fracture.
Sciatic type pain and numbness in the legs is frustrating and painful See your primary care doctor or a neurologist , orthopedic specialist for more assistance.