Hi everyone, I am certainly not a PHP expert, but based on this snipped (https://www.isitwp.com/default-post-content/) and with the help of ChatGPT I was able to create a wordpress plugin for that. The Plugin adds a Menu to the WP backend under »tools«, where you can specify default titles and default content for pages and posts.

You can download it here:
MLdefaultPostContent1

(Absolutely NO warranty! Plugin is still under development and might be buggy.)
But it works great for me! 😉

My code was also inspired by the plugin here, which did not really work for me, because it could not deal with different post types:
https://cs.wordpress.org/plugins/my-default-post-content/

Maybe someone wants to use my code / plugin. I would also be happy if a PHP pro wants to check if the code is secure and give me some feedback. Thanks and have fun!