Litho has options not only to enable/disable related posts globally but also to set it on post/portfolio level.
Enable/Disable Related Post Globally for Whole Website
Please refer to this article for more information: Theme Customizer > Layout and content > Post Single.
Enable/Disable Related Post Single Post Wise
Step 1: Go to WordPress Admin > Posts > Add/Edit Post.
Step 2: Litho Post Settings > Single Post Settings > Related post section. See below image for more information.
