Lightly season the chicken thighs with kosher salt and fresh black pepper on both sides and let sit for about 10 minutes.

Heat a couple of tablespoons of olive oil in a Dutch oven over medium-high heat. Sear the seasoned chicken thighs for 5-7 minutes per side until golden brown. Remove and set aside.

Reduce heat to medium and add diced yellow onion and minced garlic, sautéing for 2-3 minutes until golden. Add chopped celery and diced carrot, then sauté for another 5 minutes.

Pour in dry white wine and chicken broth, scraping up browned bits from the pot. Stir in crushed tomatoes and dried marjoram, adjusting seasoning with salt and pepper.

Return seared chicken to the pot, add rosemary, cover partially, and reduce heat. Simmer for 25-30 minutes until chicken is fork-tender.

For slow cooker, transfer seared chicken and sautéed vegetables to the slow cooker with liquid and crushed tomatoes. Cook on low for 8 hours.

For Instant Pot, after searing and sautéing, add liquid ingredients, seal lid, and pressure cook on high for 30 minutes. Allow natural release before serving.