Then there must be confusion with file. How about something like this?

use warnings;
use strict;

my $in = 'file'
my $out = 'file2';
open my $OUT, '>', $out or die $!;
                 
if (-s $in) {
    open my $IN, '<', $in or die $!;
    while (<$IN>) {
        my $line = $_;
        chomp $line;
        print $OUT "$line\n";
        print $OUT "you need to do this\n";
        print $OUT " \n";
    }
}
else {
    print $OUT "There is nothing to do\n";
}
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