As I had already asked in
How to store the URL's and Titles of a list of posts under same label into a String array in Blogger

And the answer given was

<b:if cond='data:blog.searchLabel'>
  <script>
    var URLArray = <b:eval expr='data:posts map (post =&gt; post.url)'/>;
    var TitleArray = <b:eval expr='data:posts map (post =&gt; post.title)'/>;
  </script>
</b:if>

Now I want is,
Suppose I have some posts under the same labels as the post I have currently opened, I want those posts to be stored in an array.

Wait, Let me explain first how my blog is made by me and how it works.

The blog which I have is blogger blog .It is blog for comics.

Supposedly I have some chapters of a manga named Dungeon Seeker. I have put the posts/chapter I posted under this manga with the label same as the name of the manga as Dungeon Seeker and some other labels which will be their genres like Action ,Adventure etc.

At the starting you can see the labels are Action,Drama,Dungeon Seeker,Fantasy.

Suppose I use a variable and make it work like the snippet below :

var getTitle="<data:post.title/>";
var getTag=getTitle.substring(0, getTitle.lastIndexOf(" Chapter"));

Now, Supposedly the post I am currently browsing is "Dungeon Seeker Chapter 1" and due to the code above getTag will store the value as "Dungeon Seeker", which is the same as the label name it is put in.

Now I want a code to store all the posts under the label name same as the getTag.

I have no problem if the method is different, but I want it to have the same concept as above and achieve what I want.

I am not sure how this might help but use the code in the below link if necessary only. https://pastebin.com/taURKjLF
The link is for RELATED POSTS WIDGET for Blogger. I am linking to it since the topic I have posted is nearly related to the idea of how the widget code is made.