Microsoft has released new free wallpaper theme packs into the Microsoft Store. There does not appear to be any unifying theme except the celebration of beauty around the world. The collections include:
World of Bamboo
One of the fastest-growing plants, bamboo is used in construction, fabric, textiles, food, musical instruments, and more. Explore some bamboo creations in this premium 20-image set in 4k, free for Windows 10 Themes.
Find World of Bamboo in the Microsoft Store here.
Take a look into the world of short- and longboards in this premium 16-image 4k set, free for Windows 10 Themes.
Find Surfboards in the Microsoft Store here.
Examine the elements of refractive and reflective light as it enters and exits various prisms in this premium 18-image 4k set, free for Windows 10 Themes.
Find Bending Light in the Microsoft Store here.
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 colour, based on the current wallpaper, go to Customize > Colors > Automatically select a primary colour from the background.