GetOptions is destructive: it consumes @ARGV as it processes. You would need to test @ARGV before calling GetOptions.

I would suggest this instead, though: Just determine what the required arguments are, and test them. In your case, it seems like the required arguments are an alternation:

unless ( $alt1 or $alt2 or ( $alt3 and $alt4 ))
{
   usage();
   exit;
}
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