If you are managing posts for a business or multiple accounts, you can use specialized tools:
Apps like Plann allow you to upload entire albums from Google Drive or Dropbox to draft posts in bulk. How to Save a Draft On Instagram
While composing a thread, swipe down or tap , then choose Save draft .
Start a new post by tapping the (create) icon and selecting your photos or videos. Apply any filters or edits and tap Next . Enter your caption and any tags.