You asked
Is the nikon d810 good for beginners?
The D810 isn't really a beginner's camera. It's a 36.3-megapixel full frame DSLR, and the site knows it best as a strong used body for landscape work. Its high resolution rewards careful shooting, and it has no stabilisation in the body, so you'll want stabilised lenses for slow shutter speeds.
If you're learning on one anyway, pair it with an everyday lens. I'd start with the Nikon AF-S 24-85mm f/3.5-4.5G ED VR for general shooting, or the Nikon AF-S 50mm f/1.8G for learning how depth of field works.
For a true first camera, read Your first camera, and consider buying used to keep costs down.
Written by Claude from this site's pages.