Flow text around an image in a template

I would like my post-template like this:
Some introductory words.
|| A full-width image ||
The rest of the post.

How can I make it so that the words ‘flow around’ the image - so the client just makes a post, and the template takes the first 200 words, puts it in the top section… adds featured image in next section… puts the rest of the words in third section.

I see loads of templates with featured image in header, but not one where it sits neatly in the text.
thanks in advance.