Normal strings created with single or double quotes (or q// and qq// operators) can be multiline: 
$ perl -le '
> use strict;
> use warnings;
> my $c = "multi line
> content spanning
> over three lines";
> print $c;
> '
multi line
content spanning
over three lines

[download]
But of course it would not be practical to use double quotes in your case, because you need double quotes within your template. However, single quotes or the q{} quote-like operator should be fine.

Otherwise, using single quotes for introducing the 'HERE' tag will prevent any interpolation: 

use strict;
use warnings;
my $chapter_template=<<'HERE';
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/T
+R/xhtml11/DTD/xhtml11.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">

    <head>
        <meta http-equiv="Content-Type" content="application/xhtml+xml
+; charset=utf-8" />
        <link type="text/css" rel="stylesheet" href="..\css\style_shee
+t.css" />
        <title>*****ebook title goes here*****</title>
        <meta name="author" content="*****ebook author name(first, las
+t) goes here*****" />
    </head>
    
    <body>
        <h2 class="ebook" id="LinkID*****current link goes here*****">
+Chapter *****current chapter number goes here*****</h2>
        <p class="ebook">*****ebook content goes here onwards*****</p>
    </body>
    
</html>
HERE
;
print $chapter_template;

[download]
This happily prints the content of the here doc.

In reply to Re: 'Here Documents' and unrecognized escapes by Laurent_R
in thread 'Here Documents' and unrecognized escapes by morelenmir

Title:
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