Hi there,
there are not action hooks such as those you find in GP Hooks.
Code method 1 would be to use the the_content filter hook:
https://developer.wordpress.org/reference/hooks/the_content/
Code method 2 is use a child theme to create your own content-{slug}.php template
Or you could do method 2 with no code and build a GP Block Element Content Template, where you can create your own layout.
Question – why inside the div.entry-content ?