Anyway I doubt that your desired "my_local" (or better named "lex-local") is what you need, since $x,$y,$z will always also belong to the outer scope, making ugly side-effects probable!

{ #outer scope
  $lamb = lambda ( $x, $y, $z ) => sub { $x + $y }
}
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the following is simple and very close but lacks the same aliasing like $_[0] does.

  $lamb = sub { my ($x,$y,$z) = @_; $x + $y }

so using Data::Alias or Lexical::Alias might be what you need to install for lexicals. If you don't wanna install XS-Moduls try working with lex-refs

  DB<20> $lamb=sub { my($x,$y)=\(@_); $$x += $$y } 
  
  DB<21> $a=10; $lamb->($a,5); print $a
15
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NOTE: Aliasing can always be achieved with * and pack-vars.