Computer Configuration > Administrative Templates > Microsoft Edge - Default Settings (users can override) > Default search provider
Both
HKLM\Software\Policies\Microsoft\Edge\Recommended
Specify the character encodings supported by the search provider. Encodings are code page names like UTF-8, GB2312, and ISO-8859-1. They are tried in the order provided. This policy is optional. If not configured, the default, UTF-8, is used. This policy is applied only if you enable the 'DefaultSearchProviderEnabled' (Enable the default search provider) and 'DefaultSearchProviderSearchURL' (Default search provider search URL) policies. Starting in Microsoft Edge 84, you can set this policy as a recommended policy. If the user has already set a default search provider, the default search provider configured by this recommended policy will not be added to the list of search providers the user can choose from. If this is the desired behavior, use the 'ManagedSearchEngines' (Manage Search Engines) policy. Example value: UTF-8 UTF-16 GB2312 ISO-8859-1