Preheat your oven to 350°F. Place the bacon slices in a large oven-safe skillet over medium-high heat and cook until evenly browned, about 10 minutes. Drain the bacon on paper towels, then crumble it once cool, leaving the drippings behind in the skillet.
Whisk the flour, kosher salt, and smoked paprika together in a bowl until combined. Coat each chicken thigh evenly in this mixture, then cook the coated pieces in the bacon drippings until browned on both sides, about 5 minutes per side. Transfer the chicken to a plate once done.
Drain all but a tablespoon of the grease from the skillet. Add the sliced red onion and apple, and cook, stirring occasionally, until the onion turns translucent and the apple softens, roughly 5 minutes. This step builds the sweet base for your cabbage.
Stir the sliced red cabbage and crumbled bacon into the onion and apple mixture. Season lightly with salt and cook, stirring often, until the cabbage begins to soften and wilt down, about 5 to 8 minutes.
Pour in the red wine vinegar and dry red wine, then stir in the brown sugar and cinnamon if using. Bring everything to a boil and let it cook, stirring occasionally, until the liquid reduces by about half, roughly 10 minutes.
Nestle the seared chicken thighs on top of the cabbage mixture in the skillet. Transfer the whole pan to your preheated oven and bake until the cabbage is fully tender and the chicken reaches an internal temperature of 165°F, about 40 minutes.