Computer Configuration > Administrative Templates > Microsoft Edge
Both
HKLM\Software\Policies\Microsoft\Edge
Encrypted ClientHello (ECH) is an extension to TLS that encrypts the sensitive fields of ClientHello to improve privacy. If ECH is enabled, Microsoft Edge might or might not use ECH depending on server support, the availability of the HTTPS DNS record, or the rollout status. If you enable or do not configure this policy, Microsoft Edge will follow the default rollout process for ECH. If this policy is disabled, Microsoft Edge will not enable ECH. Because ECH is an evolving protocol, Microsoft Edge's implementation is subject to change. As such, this policy is a temporary measure to control the initial experimental implementation. It will be replaced with final controls as the protocol finalizes.