If (-NOT ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator))
{
  # Relaunch as an elevated process:
  Start-Process powershell.exe "-File",('"{0}"' -f (($MyInvocation.PSCommandPath)+$PSCommandPath)) -Verb RunAs
  exit
}

#Start Excel
$Excel=New-Object -ComObject Excel.Application
#Open File
$FilePath='C:\Path\To\OneDrive - Company Ltd\Desktop\testing.xlsx'
$WorkBook=$Excel.Workbooks.Open($FilePath)
#Make it visible (Just to check what is happening)
$Excel.Visible=$true