On the Front Page (a static page must be assigned!), you can show a post that has been assigned a specific tag, a “featured” for example. To show a featured post on the front page, you need to assign tag (must consist of a single word!) of your selected post and set Featured Image for it. Next, go to the Customizer > Front Page Sections panel > Featured Post: there, paste the chosen tag in Tag name field and press Publish.
Please note: you need to assign a tag and a Featured Image for the post you want to show on the Homepage as Featured post.