Show first portion of post (not the_excerpt)

Hello everyone,

I’m looking to somehow make WordPress display a certain amount of a post, with a link to the full post (on all of the pages except “single pages”). A good example of this is: https://thenonist.com/. I would like all formating and images to appear in this “portion” of the post — that is one reason why I can’t use the_excerpt; it ignores images and formatting.

So, if anyone knows how I can pull this off, I would really appreciate your help. Thanks!