Computer Configuration > Administrative Templates > Google Chrome - Default Settings (users can override) > Default search provider
Both
HKLM\Software\Policies\Google\Chrome\Recommended
If DefaultSearchProviderEnabled is on, then setting DefaultSearchProviderNewTabURL specifies the URL of the search engine used to provide a New Tab page. Leaving DefaultSearchProviderNewTabURL unset means no new tab page is provided. Example value: https://search.my.company/newtab