Well, you could use do:

open my $fh, 'file' or do { something; something else; };
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But that's getting a bit obscure, so I'd probably write something a bit more expressive.

if (!open my $fh, 'file') {
  something;
  something else;
}
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Or

unless (open my $fh, 'file') {
  something;
  something else;
}
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