Dear Team, How can i duplicate the luma or blank theme and customize. Since it is not advisable to customize the blank/luma default themes. Thank you
You have to follow below tutorials for create custom theme based on luma/blank.
By default, Magento devdocs gives instruction for how to create custom store front using magento 2.
Second link from third party blog, This blog is also good for creating custom theme,
Seems like you are correct !! As per the standard never edit directly base theme like blank/luma theme !
If you would like to customize current layout/design - you need to create your own custom theme for that !!
You can override existing luma/blank theme layout into your custom theme based on your requirements !!
As suggested by Rakesh above if you wanted to create custom theme you can follow this url - https://devdocs.magento.com/guides/v2.2/frontend-dev-guide/themes/theme-create.html
But if you wanted to override existing blank/luma theme layout in your custom theme here is the reference link - https://devdocs.magento.com/guides/v2.2/frontend-dev-guide/themes/theme-inherit.html
Hope it helps to you !!