how to add meta tags to individual blogger posts

Enable Meta Tags of your Blogspot

Yes, you have to enable it manually. 

How to do it:

go to blogger dashboard > settings > Search preference > Meta Tags > description > click, "Edit" and say, "Yes" to, "Enable search description?" and save changes

SEO Optimized Blogspot Blogger Tips and Tricks

Watch this space for more tips and tricks to make your Google Blogspot Blogger SEO friendly