Facebook gives every functionality in its application that increases its user engagement, that’s why it gives a feature to save your post draft on your account. To save a draft on Facebook you need to follow the steps written below.
Open the Facebook application and make a login to your account.
On the home page you have an option to create a post, click on it.
Design your post and press the back button and the pop-up will come out to save your post.
Click on it and your post will be saved in your Facebook drafts.
Read more if you want to know more on this topic: https://ityug247.com/how-to-find-drafts-on-facebook/