Can we make Post as parent of another post in WordPress? like we do for Page i.e. Page Parent.
Or that can be done only with customization.
If already some function exists or some solution kindly post the link. i have searched on google but found nothing like.
No, you can’t. But for do this, you have the categories.
With hierarchical you could for example make a different template for any category, or simple make a category parent and other children, and with this hierarchical you get a post parent and his children.
There is a previous thread for this question: https://wordpress.stackexchange.com/questions/36300/can-posts-have-parents
With customization? YES it can, but A LOT of it. Well, basically posts and page are sharing the same database table, so posts may have parent too. But you must consider on how to add the parent ID on the table, how to get the parent post/child post data out from database, how to design the rewrite rules for child posts etc.
But again, it can be done, with a lot of work and effort.
I suggest you stick with pages, which is naturally can be nested