Computer Configuration > Administrative Templates > Microsoft Edge > Certificate management settings
Both
HKLM\Software\Policies\Microsoft\Edge
This policy enables a list of TLS certificates that should be trusted by Microsoft Edge for server authentication. Certificates should be base64-encoded. Example value: 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