In Microsoft Edge the default behaviour of “new tab” is it to open a customizable page with Microsoft Bing and other content. The content can be disabled but there is no way to change the “new tab” page completely.

Here is a PowerShell snippet to do it, tested on Windows Server 2019. Not working on Windows 10 Pro 20H2 / MS Edge 88.

if( (get-item "HKLM:\Software\Policies\Microsoft\Edge" -ea Ignore) -eq $null) {
    New-Item "HKLM:\Software\Policies\Microsoft\Edge"
}

if( (Get-ItemProperty -Path "HKLM:\Software\Policies\Microsoft\Edge" -Name NewTabPageLocation -ea 0) -eq $null ) {
    New-ItemProperty -Path "HKLM:\Software\Policies\Microsoft\Edge" -Name NewTabPageLocation -PropertyType String -Value "https://google.de"
} else {
    Set-ItemProperty -Path "HKLM:\Software\Policies\Microsoft\Edge" -Name NewTabPageLocation  -Value "https://google.de"
}

Get-ItemProperty -Path "HKLM:\Software\Policies\Microsoft\Edge" -Name NewTabPageLocation 

Update…

It does not work on a machine that is not domain joined. 🙁

Here I found a possible solution for Windows 10: