Microsoft Edge will get full support for Variable Fonts soon. The feature will be deployed with the next release of EdgeHTML. This will allow the browser to render rich typography on all web sites.
Variable Fonts allow developers to adjust their appearance in different ways, so a single font looks like multiple fonts. The changes can be applied dynamically. It is possible to tweak font attributes like weight, width, and slant on-the-fly. Also, this capability can be used to create beautiful animations with fonts.
Starting in Windows 10 Build 17120, you can try the Variable Fonts feature in action.
To demonstrate variable fonts support in Edge, Microsoft provides a new immersive developer guide on their Edge Test Drive web site: Variable Fonts.
Microsoft, Apple, Adobe, Google, and others collaborated to define a standard for OpenType Variable Fonts. Learn more about Variable Fonts here.
It is worth mentioning that Google Chrome and Firefox already support Variable Fonts. In Firefox, variable fonts are an experimental feature and not yet enabled by default.