How about an app that limits more many articles or blog posts a guest can read.

So let’s say a guest lands on one of our articles or blog posts. They get to read a set amount of free articles/blogs then they get a paywall that prompts the guest that they need to subscribe to our website to continue to access the content.

An example of this is leaky paywall for wordpress
https://wordpress.org/plugins/leaky-paywall/

This is just what I am after but for Joomla

After a user gets the paywall message they can buy a subscription through PayPlans and get access to all articles/blog posts.