New users to Mastodon may notice there is no built-in feature for "Quote Posts" like in Twitter or Threads.
Until recently the Mastodon project had been resistant to including Quote Posts in the platform, however it is now officially listed on the Project Roadmap as being considered for future inclusion.
While most uses of Quote Posting on microblogging platforms are benign, there is some research that indicates Quote Posts on other platforms are commonly used to "dunk" on users. The desire of the Mastodon project team is to include this feature natively in a privacy preserving way, so that users who do not wish to have their content quoted can opt-out.
Some third-party client apps include a Quote Post function by simply copying the full URL to the post and including it in the body of the new post, which will then embed the original content in the new post. Unfortunately not every client will render the resulting post the same way.