if ($FileExt eq ".pdf"){ 
  if  (length($FileExt) > 3){

##</code><code>##

while (my $filename = readdir(DIR)){

  next unless (-f $filename);
  next if ($filename eq $SumRptNam);
  
  if ($filename =~ /\.(pdf|xlsx)$/){
    my $FileExt = $1;
    if ($FileExt eq 'pdf'){
      # do X to pdf
    } 
    if ($FileExt eq 'xlsx'){
      # do Y to xlxs
    } 
    # do Z to both
  }
}