Taken from https://techcommunity.microsoft.com/t5/azure-database-support-blog/auto-scale-azure-sql-elastic-pools/ba-p/4011610

dtu_scaleup.ps1

# script taken from https://techcommunity.microsoft.com/t5/azure-database-support-blog/auto-scale-azure-sql-elastic-pools/ba-p/4011610
param (
    [Parameter (Mandatory=$false)]
    [object]$WebhookData
)

# Import the Az module
Import-Module Az.Sql

# If there is webhook data coming from an Azure Alert, go into the workflow.
if ($WebhookData) {
    # Get the data object from WebhookData
    $WebhookBody = (ConvertFrom-Json -InputObject $WebhookData.RequestBody)
    # Get the info needed to identify the SQL database (depends on the payload schema)
    $schemaId = $WebhookBody.schemaId
    Write-Verbose "schemaId: $schemaId" -Verbose
    if ($schemaId -eq "azureMonitorCommonAlertSchema") {
        # This is the common Metric Alert schema (released March 2019)
        $Essentials = [object] ($WebhookBody.data).essentials
        Write-Output $Essentials
        # Get the first target only as this script doesn't handle multiple
        $alertTargetIdArray = (($Essentials.alertTargetIds)[0]).Split("/")
        $SubId = ($alertTargetIdArray)[2]
        $ResourceGroupName = ($alertTargetIdArray)[4]
        $ResourceType = ($alertTargetIdArray)[6] + "/" + ($alertTargetIdArray)[7]
        $ServerName = ($alertTargetIdArray)[8]
        $ElasticPoolName = ($alertTargetIdArray)[-1]
        $status = $Essentials.monitorCondition
    }
    else {
        # Schema not supported
        Write-Error "The alert data schema - $schemaId - is not supported."
    }
}
if (($status -eq "Activated") -or ($status -eq "Fired")) {
    Write-Output "resourceType: $ResourceType"
    Write-Output "serverName: $ServerName"
    Write-Output "resourceGroupName: $ResourceGroupName"
    Write-Output "subscriptionId: $SubId"

    # Import the Az module
    Import-Module Az.Sql

    # Authenticate to Azure using Managed Identity
    Connect-AzAccount -Identity 

    # Because Azure SQL tiers cannot be obtained programatically, we need to hardcode them as below.
    # Check the values for your Azure SQL elastic pool and replace them within the below parameter $TargetDtu 

    $TargetDtu = @(50,100,200,300,400,800,1200,1600,2000,2500,3000)

    $currentDatabaseDetails = Get-AzSqlElasticPool -ResourceGroupName $ResourceGroupName -ServerName $ServerName -ElasticPoolName $ElasticPoolName

    #Replace the highest value with the values from your Azure elastic pool service tier
    if ($currentDatabaseDetails.DTU -eq "3000") {
        Write-Output "DTU database is already at highest tier (3000)"
    }
    else {
        for ($i=0; $i -lt $TargetDtu.length; $i++) {
            if ($TargetDtu[$i].equals($currentDatabaseDetails.DTU)) {
                Set-AzSqlElasticPool -ResourceGroupName $ResourceGroupName -ServerName $ServerName -ElasticPoolName $ElasticPoolName -Dtu $TargetDtu[$i+1]  
                break                 
            }
        }
    }
}