localtime takes an argument of the form returned by the time function. e.g epoch seconds. Which is just a number that you can subtract from. So

my $now = time;
for my $i (0..9) {
    print "$i days ago... ", scalar localtime $now - $i * 86400, "\n";
}
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should work. 86400 is the number of seconds in a day. You could also do this using Date::Manip.

And you could get fancier w/ the date printout than this is--it's just an example.