How to convert an existing wordpress site into directory base multisite?

Question

I want to update one of my sites ( https://mcqacademy.com/ ) into directory base multisite. Problem is - the basic way of upgrading an existing Wordpress site to multisite is to make a sub-domain base multisite.

I want to know is there any plugins or tutorial or any pro resources that will make my site to directory base multisite so that I will not need to transfer my existing data (post, taxonomies, meta etc) manually ...

Again, Because my installation is not new, the sites in my WordPress network must use sub-domains. But I want sub-directory base network. See the screenshot -

Thanks in Advance!

Answer 1

Article in Codex: https://codex.wordpress.org/Create_A_Network

"You are given the choice between subdomains and subdirectories. Except when one is restricted by existing settings and restricts one's options. "

and restrictions https://codex.wordpress.org/Before_You_Create_A_Network#WordPress_Settings_Requirements

"You cannot choose Sub-directory Install (for a path-based network) if your existing WordPress installation has been set up for more than a month, due to issues with existing permalinks. (This problem will be fixed in a future version. See Switching network types for more information.)