Post Subtitle

I am unable to recreate a post subtitle that appears on the below post link:
https://andersnoren.se/themes/eksell/white-oval/

Image: https://imgur.com/a/MX8eqER

Any text I create shows below the featured image
https://www.muthagoose.art/2022/01/07/boombox-mural/

Things I tried: Create a template, however it gave me a full width template without the left sidebar menu.