trying to set up the theme I faced one simple but strange problem. If I look trough your examples and videos I see the extracts of posts and then button "Read more".
In my case, every post is shown in full and I have no more ideas how to make it similar to yours.
while editing a post you can add the Read More Tag by clicking the corresponding button in the toolbar of the old WordPress editor or add the "More" block in WordPress' new block editor.
Thank you for the fast and prompt reply. I spent a week... but did not have any plugin for that function. Now it works properly.