Get-Content
produces an array of strings, where each string contains a single line from your input file, so you won’t be able to match text passages spanning more than one line. You need to merge the array into a single string if you want to be able to match more than one line:
$text = Get-Content $file | Out-String
or
[String]$text = Get-Content $file
or
$text = [IO.File]::ReadAllText($file)
Note that the 1st and 2nd method don’t preserve line breaks from the input file. Method 2 simply mangles all line breaks, as Keith pointed out in the comments, and method 1 puts <CR><LF>
at the end of each line when joining the array. The latter may be an issue when dealing with Linux/Unix or Mac files.