1. From Customize section, go to Homepage Sections Options.
2. From Homepage Sections Options, you will see Latest Post Section Options.
3. In Latest Post Section you will see:

• Enable Section: It allows to enable/disable the Recommended Posts Section.
• Title: It allows to change the title of the section.
• Sub Title: It allows to change the subtitle of the section.
• Exclude Categories: With this option, you will be able to exclude the category that you don’t want to display in Latest Post Section.
• Slider Speed: Allow to control the slider speed.
• Click “Save & Publish” button to save changes.

For image size refer to below link :

Image size