How Set Schema JSON-LD from Meta Option

First, you need to support Schema in your desire post type, See the documentation. Then in your single post type you will see Review & Schema Settings Meta Box.

You need to configure the settings look like the following screenshot.

1. Schema Tab: First click on Schema tab to add custom Google Schema JSON
2. Custom rich snippet? (Manual) : You must enable this option to set your custom Schema JSON Data it will override auto-generated settings.
3. Rich snippet category: Which snippet category you want to show select from here.
   1. Article
   2. News Article
   3. Blog Posting
   4. Event
   5. Local Business
   6. FAQ
   7. Service
   8. Q & A
   9. How To
   10. About
   11. Contact
   12. Person
   13. Movie
   14. Audio
   15. Video
   16. Breadcrumb
   17. ItemLists
   18. Product – Woocommerce & EDD [Pro]
   19. Course [Pro]
   20. Job Posting [Pro]
   21. Recipe [Pro]
   22. Software App [Pro]
   23. Image License [Pro]
   24. Special Announcement [Pro]
4. Category schema field: When you choose the Rich snippet category then the necessary meta field will be shown.

Note: You must fill up the required red * fields otherwise it will give a schema error.

Google Schema Validation Check: After fill up all necessary field check your page/post URL from here. Look like the following.