How can I add pages in All posts category like page 1, page 2, page 3? Please help me out.
please correct me If I am wrong, but do you speak about possibility to have subcategories under the All posts? Maybe you could provide more details in what do you aim to achieve?
Now you can create categories and aggregate your posts to it: https://support.wix.com/en/article/creating-categories-in-the-new-wix-blog