As the home page of my blog I’ve a static page.
There I want to show the navigation of the site.
All the above words are hyperlinks.
Now what I need is, when a user clicks on tag1 under subcategory1 in category2, all the posts of category2, in subcategory1 having tag1 shall be returned.
is it possible to have a URL like domain.com/category2/subcategory1/tag1 for this purpose?
Given the way categories & tags are setup in WordPress this would not work from a logical standpoint. The issue here is that tags have no way to be connected directly to a category, they are mutually exclusive from each other. The subcategories would work because a subcategory is directly related to is parent category but tags are non hierarchical and have no parent/child relationship capabilities on purpose.
It is not possible in vanilla WordPress as the tags, and categories are separate entities.
Categories would offer you a hierarchical parent/child relationship, and could accomplish this.
Alternately, if you wish to retain the tags as you have them, you could use WordPress SEO to rewrite the tag URLs, and essentially ‘spoof’ the URL.
I hope that helps!