Sheet Pan Roasted Sweet Potatoes and Chicken

medium/large sweet potatoes, peeled and diced into 1/2-inch pieces

to 4 tablespoons olive oil, divided

kosher salt, or to taste

freshly ground black pepper, or to taste

to 1.50 pounds boneless skinless chicken breasts, cut into bite-sized pieces

medium/large red onion, peeled and cut into chunks or wedges

coriander, or to taste