$packagePath = "path\to\languagepack.cab" dism /online /add-package /packagepath:$packagePath
Alternatively, via PowerShell (offline method): Microsoft Windows 10 Language Pack Offline Install -Extra
In Windows 10, Microsoft transitioned from monolithic language packs to a modular structure to save disk space and improve installation speeds. This architecture divides language support into two distinct categories: $packagePath = "path\to\languagepack