Pat dry the chicken thighs with paper towels and season generously with salt and pepper on all sides.
Place the thighs in the crockpot, arranging them in a single layer, skin side down if any skin remains.
In a small bowl, whisk together the lemon juice, minced garlic, lemon zest, and chicken broth until well combined.
Pour the lemon mixture evenly over the chicken in the crockpot, then add sprigs of thyme or rosemary if using.
Cover the crockpot and cook on low for 6 to 7 hours, until the chicken is tender and easily pulls apart, and the aroma of citrus fills the kitchen.
Once cooked, carefully lift the chicken out with tongs and transfer to a serving plate. Let it rest for 5 minutes.
If the sauce looks too thin, turn the crockpot to high and cook uncovered for 10 minutes until it thickens slightly and becomes glossy.
Drizzle the chicken with a little olive oil and additional lemon juice if desired, then spoon the glossy, fragrant sauce over the top.
Garnish with extra herbs or lemon slices and serve hot with your favorite side dishes, enjoying the vibrant aroma and tender texture.