SharePoint Online: Get Lookup Column Value using Powershell

Requirement: Get Lookup field value in SharePoint Online using PowerShell.

Scenario: We've a parent list called "Parent Projects" and child list "Project Milestones". The "Parent Project Name" field in the child list is being looked up from the parent list's "Project Name" field. Here is my PowerShell script to get lookup field values.

PowerShell to Get Lookup Field Value in SharePoint Online: 
To retrieve the value of lookup column in a SharePoint Online list, use this PowerShell.

#Load SharePoint CSOM Assemblies
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"

#Set parameter values
$SiteURL="https://crescent.sharepoint.com/Sites/PMO"
$ListName="Project Milestones"
$FieldName="ParentProjectName" #Internal Name
$ListItemID="25"

#Get Credentials to connect
$Cred= Get-Credential
$Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.Username, $Cred.Password)
 
#Setup the context
$Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
$Ctx.Credentials = $Credentials

#Get the List Item
$List = $Ctx.Web.lists.GetByTitle($ListName)
$ListItem = $List.GetItemById($ListItemID)
$Ctx.Load($ListItem)
$Ctx.ExecuteQuery()

#Get Lookup Field Value
$Lookup = [Microsoft.SharePoint.Client.FieldLookupValue]$ListItem[$FieldName]
Write-host $Lookup.LookupValue

SharePoint Online: Retrieve Multi-Value Lookup Field Values using PowerShell:
When "Allow Multiple Values" is enabled, it becomes multi-valued lookup column. So the script to read the lookup column goes here.

#Load SharePoint CSOM Assemblies
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"

#Set parameter values
$SiteURL="https://crescent.sharepoint.com/sites/PMO"
$ListName="Projects"
$FieldName="ParentProjects" #Internal Name
$ListItemID="25"

#Get Credentials to connect
$Cred= Get-Credential
$Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($Cred.Username, $Cred.Password)
 
#Setup the context
$Ctx = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
$Ctx.Credentials = $Credentials

#Get the List Item
$List = $Ctx.Web.lists.GetByTitle($ListName)
$ListItem = $List.GetItemById($ListItemID)
$Ctx.Load($ListItem)
$Ctx.ExecuteQuery()

#Get Multi-Lookup Field Value
$LookupValueCollection = [Microsoft.SharePoint.Client.FieldLookupValue[]]$ListItem[$FieldName]

Foreach ($LookupValue in $LookupValueCollection)
{
    write-host $LookupValue.LookupValue
 
}

Here is my another post on updating lookup column value in SharePoint Online using PowerShell Update Lookup Field using PowerShell in SharePoint Online