Computer Configuration > Administrative Templates > Google Chrome - Default Settings (users can override)
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HKLM\Software\Policies\Google\Chrome\Recommended
Setting the policy specifies the locale Google Chrome uses. Turning it off or leaving it unset means the locale will be the first valid locale from: 1) The user specified locale (if configured). 2) The system locale. 3) The fallback locale (en-US). Example value: en