How can I write PowerShell to Break Permission Inheritance for all document libraries in a Site

Hi, @adil ,

I assume your are using SharePoint On-Premise. Please have a try with the script below

#Configuration Parameters  
$WebURL="siteURL"  
  
   
#Get the List  
$Web = Get-SPWeb $WebURL  
$Lists = $web.Lists  
Foreach($List in $Lists)  
{  
 #Return only document libraries  
 if ($List.baseTemplate -eq "DocumentLibrary")  
 {  
 #Check if the library has unique permission  
 if ($List.HasUniqueRoleAssignments -eq $False)  
 {  
 $List.BreakRoleInheritance($True)  
 Write-host $List.Title "Stopped Inheriting Permissions from the parent." -f Green  
 }  
 else  
 {  
 write-host $List.Title "List is already using Unique Permissions!" -f Red  
 }  
 }  
  
}  

If the answer is helpful, please click Accept Answer and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.