You are using the single-argument form of bless, which does not bless $bob into the class Manager:

my $bob = Manager->new_worker(name   => "Bob",
                   age => 40);
print $bob,"\n";
# Worker=HASH(0x15debec)
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To properly enable inheritance, you must also properly bless every object into the right class. I don't know where you copied your constructor from, but you shouldn't throw away the package name to use (you put it into $invocant), but pass it to bless as the second argument:

sub new_worker { ## Constructor.
    my $invocant = shift;
    # my $class = ref($invocant);
    my $self = {
    name   => "Jhon Do",
    age    => 32,
    @_ ,
    }; 
    bless $self, $invocant;
    return $self;
};
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Also, you should consider renaming your new_worker method to new, as is customary with constructors.