Is it necessary to make different sitemap for each post or we just need to do it only once?

No, you do not need to create a separate sitemap for each post in Google Search Console.

A sitemap is an XML file that contains a list of URLs on your website that you want search engines to crawl and index. The purpose of a sitemap is to help search engines discover new content and understand the structure of your website.

You can create a sitemap that includes all the URLs on your website, including your blog posts. Once you create the sitemap, you can submit it to Google Search Console so that Google can crawl and index the pages on your website.

If you update your blog frequently with new posts, it is a good idea to generate a new sitemap regularly and submit it to Google Search Console. This way, Google can quickly discover your new content and index it in the search results. However, you do not need to create a separate sitemap for each individual post.