Grant access to "SharePoint Service Administrator" domain group using PowerShell?

Use the script below to automatically add user in the domain group -

$AdminURL = "https://domain-admin.sharepoint.com/"
$AdminName = "user.domain.onmicrosoft.com"
$SiteCollURL = "https://domain.sharepoint.com/sites/example"
$SiteCollectionAdmin = "[email protected]"


$SecurePWD = ConvertTo-SecureString "Password" –asplaintext –force 
$Credential = new-object -typename System.Management.Automation.PSCredential -argumentlist $AdminName, $SecurePWD 
Connect-SPOService -url $AdminURL -credential $Credential
Set-SPOUser -site $SiteCollURL -LoginName $SiteCollectionAdmin -IsSiteCollectionAdmin $True

I was able to achieve it through PnP Powershell. Below is the PnP powershell script to update "SharePoint Service Administrator" as SCA for all site collections:

$credentials=Get-Credential
$URL="https://Company.sharepoint.com"
Connect-PnPOnline -Url $URL -Credentials $credentials
$siteColl=Get-PnPTenantSite 
$loginName = "c:0t.c|tenant|ID Of SharePoint Service Administrator domain group in your tenant" 
foreach($site in $siteColl)
{ 
write-host -ForegroundColor Green "Updating SCA for site: " $site.Url  
Connect-PnPOnline -Url $site.Url -Credentials $credentials  

$scaColl=Get-PnPSiteCollectionAdmin   
foreach($sca in $scaColl)  
{          
    Add-PnPSiteCollectionAdmin -owners $loginname 
} 
}