Microsoft has added a new theme pack to the Microsoft Store for Windows 10 users. Titled Panoramic Train Views PREMIUM, the new theme pack contains 10 high-quality 4K wallpapers, the description of which reads as follows:
Take the long route with these sweeping views from train windows. These 10 4k images are premium for Windows themes and are to be used as desktop wallpaper only.
After downloading the collection, go to Start > Settings > Personalization > Themes and click on the theme you prefer.
To apply and change to the most appropriate color, based on the current wallpaper, go to Customize > Colors > Automatically select a primary color from the background.