#!/usr/bin/perl -w
use strict;

...

my @directories = qw( /files1 /files2);

my $min_size = 1024; 
my $max_size = 1048576; #1MB

for my $dirs (@directories) {
  
    push @files, grep { -f && -s _ >= $min_size && -s _ <= $max_size} read_dir( $dirs, prefix => 1 );  

    print "\n These files are passed the size limit: @files\n";
 
}

...