First: please recognize that despite what you may read on click-hungry review sites or fan-fueled forums, every DSLR and mid-to-higher range mirrorless camera on the market will be stellar for the purposes described. Any differences are details — every option is an A and it's then down to arguing over A+ or A++, as well as subjective factors or very technical differences in niche cases. And certainly anything you get will feel quite updated, as your current camera is over a decade old.

So that said, I'm going to address your two specific concerns.

First, RAW images do not have characteristics like "austere". Anyone who says otherwise is probably selling you something. It's all down to processing. Nikon's own software or third party options like Lightroom can easily given you results that are dull, stark, or vibrant depending on your taste. For that matter, you can do the same with in-camera JPEG settings.

Second, this is a very capable general purpose camera. As I noted to start, like any other option you pick it can handle the situations you describe with aplomb. I suspect that any description you've found like "best for nature" is from someone grasping at straws to find some distinction to make. Don't worry — it will be great.