To keep a kitchen looking "rich and sumptuous" rather than dark when dark red paint is already being used, I would recommend utilizing rich wood tones. Cherry, for example, can pair super well with dark red. It has a rich warm shade to it, which can help elevate the space to make it feel sumptuous, but it doesn't have to be a dark shade. It complements dark red well while also offering a bit of a contrast.
While playing with Japandi looks for my business Japantastic, I learned dark red kitchens need texture. Light wood accents, like shelves or a thin countertop edge, warm things up without feeling heavy. Brass or brushed gold handles add a nice touch too. A simple trick is painting the ceiling a warm white or light cream. It makes the whole kitchen feel more spacious and inviting. If you have any questions, feel free to reach out to my personal email