All Windows 10 themes are stored in this folder by default. If you want to add more resources to a current theme, you can do that by going to the following folder. It has a huge variety of themes including themes of our favorite fan fiction movies and seasons.
Personally I liked this website the best. You can simply download themes from other websites too. Open the store, sign in to your Microsoft account and install whatever theme you like. You can do so by following these instructions You can find Windows themes in the Microsoft store. You can also download Windows 10 themes from the official Microsoft Store and also third-party sites that collect and create different customized themes. There are some themes that are present in Windows by default. A theme can be applied to the user interface by simply clicking on the downloaded theme file. to quickly customize the Windows 10 user interface. Windows themes are a collection of background pictures, menu colors, system sounds etc.