Hi,
<blockquote>But I didn’t found How to create custom layout file (.php) like default.php which will hold the HTML generation of site’s front-end design? Template is always display html/output from default.php for all menu item/pages.</blockquote>
This default.php file is located in pluginssystemjat3jat3base-themesdefaultpage folder.
<blockquote>Kindly help for How can we create custom layout file like xyz.php which will which will hold the HTML generation of site’s front-end design for specific page/menu item ?</blockquote>
With templates based on JAT3 framework, you can create & put a new layout(i.e newlayout.xml) in templatesja_templateetclayouts folder, then use profiles with selected layout to assign to specific page/menu items in Template Manager >> JA_Template_Default >> Page & Menu assignments.
Leo