It depends on what type of schema.org you want to add.
The theme you use should provide basic structural schema.org markup of your pages and posts.
If you want specific schema.org markup for events, products, etc. you can try using this plugin: https://en-ca.wordpress.org/plugins/all-in-one-schemaorg-rich-snippets/
^V
thank you and how make video-sitemap in VideoObject in
Favourite All In One Schema.org Rich Snippets Download
All In One Schema.org Rich Snippets
Are you referring to an actual XML sitemap? You would need a plugin for that. XML sitemaps and rich snippets are 2 separate things.
For sitemap, you can try this:
https://wordpress.org/plugins/google-video-sitemap-feed-with-multisite-support/
Or if you use Yoast SEO, you can get their premium version:
https://yoast.com/wordpress/plugins/video-seo/
^V
