How to modify the WP posts layout?

Hello,

I hope everyone is sound and safe on your side.

I have a plugin (used to hide/show content by clicking on a button) inviting to place a shortcode before and after the content to hide. Here I am trying to hide/show the content of posts, but I do not know exactly where to place these shortcodes.

The part of the post I need to hide/show is the texts part of the post ‘only’. The one we edit on the text editor (Not the featured image or any other element.) And I need to make that change for all posts, not individually. And I didn’t manage to find the portion of code representing this part only.

Can you help me to place these shortcodes? Thank you very much.