use Text::Template;

my $template = Text::Template->new(
    type => "FILEHANDLE",
    source => *DATA,
);

my $text = $template->fill_in(
    hash => {
        placeholder1 => "chicken",
        placeholder2 => "dog",
    },
);

print $text;

__END__
This is text with { $placeholder1 }.
It can be with { $placeholder2 } too.
{ $placeholder1 } can appear more than one time in the text.