I know next to nothing about bioinformatics but perhaps this suggestion helps.

#!/usr/bin/perl
use warnings;
use strict; 
use Bio::DB::GenBank;
use Bio::SeqIO;  

my $gb   = new Bio::DB::GenBank; 
my $acc  = "NM_021817";  
my $seq1 = $gb->get_Seq_by_acc($acc);
my $sequence = $seq1->seq;

for my $feat ($seq1->get_SeqFeatures){
  if ($feat->primary_tag eq 'CDS'){
    print $feat->get_tag_values('product'),"\n";
    print $feat->get_tag_values('gene'),"\n";
    
    my $start = $feat->start;
    my $len   = $feat->length;
    my $cds = substr($sequence,$start-1,$len);
    use Text::Wrap; # put this at top
    $Text::Wrap::columns = 71;
    print wrap('', '', $cds);
  }
}
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