How to override default Regional Format settings in Windows 10

Depending on where you are, and what locale you work with, and lastly which locale you belong to, Windows 10 doesn’t offer many choices for its Region settings. The standard region settings for Windows 10 lets you select one set of format for the calendar and more. This, however, has changed from Windows 10 v1809. You can override default regional format settings in Windows 10Improved local experience.

Open Settings > Time and Language > Region

Settings such as Calendar, First day of the week, Dates, Times, and Currency, you can change under Regional format.
After changing, you will not have to reboot your Windows 10 PC. However, some of the apps will have to close and launched again to apply the new format. So if you need to use apps which are of a different locale, the changes will appear only when you relaunch the app.
This local format will be used for navigation, menus, messages, settings, and other topics. Under Languages, look for a link which says "Add a Windows display language with local experience packs".

Local Experience Packs are Microsoft Store apps that deliver Windows display language quality improvements. When you click on the link, it will download from the Microsoft Store.

Lastly, Windows has started utilizing Artificial Intelligence (AI) and neural network-based Machine Learning (ML) for Windows localization. As the number increase, Machine language improvements, and user feedback will help make translations better, and make it available to more and more languages.