use List::MoreUtils qw(each_arrayref);

my @content =
    map {
        open(my $fh, '<', $_) or die $!;
        [<$fh>]
    }
    grep {-f}
    glob '*.csv'
;
my $iterator = each_arrayref @content;
while (my @file_lines = $iterator->()){
    
    print @file_lines;
}