Request: GET https:///wp-json/wp/v2/posts
Header: Authorization : Basic base64encoded 

Sample request: GET https:///wp-json/wp/v2/posts
Header: Authorization : Basic eGw2UllOdFN6WmxKOlNMRWcwS1ZYdFVrbm5XbVV2cG9RVFNLZw==
Example =>  username : testuser and password : password@123