I found an answer to this question in a Reddit, which in turn referenced this blog: https://www.meziantou.net/set-a-blank-page-for-new-tabs-in-microsoft-edge.htm

I like Stack Overflow, however, so I wanted to have the question and answer available here. The solution is a registry hack (wow Microsoft, really?). You can either manually update the registry or run the following command in PowerShell (running as Administrator):

New-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Edge" -Name "NewTabPageLocation" -Value "google.com" -PropertyType String -Force

Note that the example above sets new tabs to load www.google.com by default, so change that as needed for your desired behavior.

For me the change took effect immediately, nothing more needed, but the solution mentions opening "edge://policy/" and click "Reload Policies" or restart Edge, so you may need to do that as well.