Hi Rashmi,
Thanks for writing in!
To reduce the gap and font size of the heading you need custom CSS.
Please add this CSS to your Theme Option -> CSS and let us know if that works.
.x-header-landmark {
padding: 10px 0px !important;
}
.h-landmark, .h-landmark.entry-title {
font-size: 20px !important; /* you can change this size */
}
Dont forget to clear your plugin cache before testing the changes.
If you would like to learn CSS, I am sharing few resources that you take a look to get started with CSS and an interesting tool that you can use to speed up the development process.
I recommend you to watch following video that will help you to get started with CSS.
https://www.youtube.com/watch?v=MFR4WXiLzpc
Sometimes it can get a bit difficult to find out the right selector to be able to write the required CSS codes. A handy tool that can help you in this is Google Chrome dev tools. I am sharing the resource that you can refer to get started with dev tools.
https://developers.google.com/web/tools/chrome-devtools/css/
https://developers.google.com/web/tools/chrome-devtools/
https://www.youtube.com/watch?v=tP_kXBJWPhQ&t=200s
Hope this helps!