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"

$UserName = ""
$Password = ""
$Url = ""
$SecurePassword= ConvertTo-SecureString $Password –asplaintext –force
$credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($UserName,$SecurePassword)

$clientContext = New-Object Microsoft.SharePoint.Client.ClientContext($Url)
$credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($UserName,$SecurePassword)
$clientContext.Credentials = $credentials
$Web = $clientContext.Web
$clientContext.Load($Web)
$lists = $Web.Lists
$clientContext.Load($lists);
$list = $lists.GetByTitle("List Title")
$clientContext.Load($list)
$clientContext.Load($list.Fields)
$field= $list.Fields.GetByInternalNameOrTitle("Order");
$clientContext.Load($field);
$clientContext.ExecuteQuery();
$field.SchemaXml = $field.SchemaXml.Replace("Hidden=""TRUE""","Hidden=""FALSE""");
$clientContext.ExecuteQuery();