What settings are recommended for shots of the sunset/ sunrise without having the foreground objects silhouetted? Or is it only achievable by stacking multiple images in Photoshop?
For an image like this, if you don't want to process multiple exposures in Photoshop you could use a graduated ND filter. Since the skyline is fairly straight a hard graduated 2 or 3 stop filter might suffice. With the dynamic range of modern cameras you could could also probably use a graduated filter in postprocessing without having noticeable issues.
In addition to reading your Nikon D810 user manual, about "Active D-Lighting", "Bracketing", "HDR" photography, "Autoexposure Lock" and using Manual exposure settings, you might find these questions / answers in the Tags Section above, help somewhat for your problem:
This can be achieved using a tripod. You need to shoot multiple exposures, minimum 3 clicks. First a normal exposure, second one to be a under exposed image (bring the light meter 2 f stops low.), 3rd one over exposure the image (increase the meter to 2 f stops up). If you check these 3 images you will see, one will be neutral, 1 will orange sky, one with the subject bright. Now merge these 3 images using image editing tools like Lightroom or Photoshop. This technique is also known as HDR imaging. There are HDR softwares available online, where you can upload these 3 images and they will give you a combined version. If your camera has a built-in HDR no need of any softwares to achieve this.Hope this help