Short answer (assuming you just mean working in a clinic): No.
Long answer: If the EM Physician is also boarded in a different specialty, they could transition to working in that other specialty as well. But that would mean that they either did two residencies or a combined residency.
Burnout among EM physicians is more of a myth. It may have applied when the majority of EM physicians were individuals who trained in other specialties and just ended up working in EDs, but the burnout among residency trained board-certified emergency providers is no higher than the burnout in any other medical specialty.