An interesting twist is to dispense with the dispatch table:

use strict;
use warnings;

my %params = (
   'default-0' => ['lakja', 'haljl', 'alka'],
   'default-1' => 'abc',
   'default-2' => [1, 54, 83, 23],
   'default-5' => '2019-06-26 00:00:10',
   'default-10' => 'Nothing to see here',
);

for my $key (sort keys %params) {
    next if $key !~ /^default-(\d+)/;

    my $sub = main->can("HandleParam$1");

    if ($sub) {
        $sub->($params{$key});
    } else {
        warn "Don't know how to handle 'default-$1'";
    }
}
...
[download]

which prints:

default-0: lakja haljl alka
Don't know how to handle 'default-10' at noname1.pl line 20.
default-1: abc
default-2: 1 54 83 23
default-5: 2019-06-26 00:00:10
[download]

where the second line is a warning line. Using this technique means you only need to create correctly named handler subs to add support for new fields and you get told if there is a missing handler. Both features make maintenance much easier!