Hi @Shardendu_Jha,
GraphQL is supported in AEM on-premise version starting from AEM 6.5.10 - release notes so it will work on AEM 6.5.13 as well.
Please be aware that on AEM 6.5.x GraphiQL is available under /content/graphiql.html and may not be available directly as an option in the menu - of course first you have to install GraphiQL Content Package.
You can also have a look on this article that describes step by step how to configure it:
All the packages you can find under software distribution portal (you will need your Adobe ID and appropriate level of access to download packages). There is no dedicated package for on-premise version, and according to Adobe documentation you should use package that is provided for AEM as a Cloud. So after you login to Software Distribution please switch to AEM as a Cloud Service section to find the package.
Here is a link to the latest available version: https://experience.adobe.com/#/downloads/content/software-distribution/en/aemcloud.html?package=/con...