I think I know what you're looking for, but there are a couple of problems to resolve, first.

Let's start with how you name modules. Given the two names you have (ABC::plot_XML.pm and ABC::plot_BLABLA.pm), here's what you need:

1. A directory somewhere in @INC (which usually includes '.') named 'ABC'
2. Two files in that directory, named 'plot_XML.pm' and 'plot_BLABLA.pm'
3. These files have statements package ABC::plot_XML.pm; and package ABC::plot_BLABLA.pm, respectively.

I suggest a quick review of [doc://perlmod], as it covers the basics nicely.

Now, to find which 'ABC' modules are available from within your script 'abc.pl', you can use [cpan://Module::Find]:

use Module::Find;
# my @found = findsubmod('ABC');  #if you want all ABC::* modules
my @found = grep { m/^ABC::plot_/ } findsubmod('ABC');  #all ABC::plot_* modules