Computer Configuration > Administrative Templates > Microsoft Edge
Both
HKLM\Software\Policies\Microsoft\Edge
Specify origins to run in an isolated process. By default, Microsoft Edge isolates pages from each Site into its own process. This policy enables more granular isolation based on Origin rather than Site. For example, specifying https://subdomain.contoso.com/ will cause pages from https://subdomain.contoso.com/ to be isolated in a different process than pages from other Origins within the https://contoso.com/ Site. If you enable this policy, each of the named origins in a comma-separated list will run in its own process. If you disable or don't configure this policy, pages will be isolated on a per-Site basis. Example value: https://contoso.com/,https://fabrikam.com/