how to creat a post content template and use it on each post content creation

Hi there,

You would just need to create a Block element Content Template and use Posts > All Posts for the display rule:
https://docs.generatepress.com/article/block-element-content-template/

The dynamic blocks and data would be helpful:
https://docs.generatepress.com/article/dynamic-blocks/
https://docs.generatepress.com/article/dynamic-data/

Let me know if this helps :)