Computer Configuration > Administrative Templates > Microsoft Edge
Both
HKLM\Software\Policies\Microsoft\Edge
OBSOLETE: This policy is obsolete and doesn't work after Microsoft Edge 84. This policy doesn't work because this policy allowed these features to be selectively re-enabled until Microsoft Edge version 85. The Web Components v0 APIs (Shadow DOM v0, Custom Elements v0, and HTML Imports) were deprecated in 2018, and have been disabled by default starting in Microsoft Edge version 80. If you set this policy is set to True, the Web Components v0 features will be enabled for all sites. If you set this policy to False or don't set this policy, the Web Components v0 features will be disabled by default, starting in Microsoft Edge version 80.