You can create ghost posts using the Threads API. Ghost posts allow you to create text posts which will be active for 24 hours and automatically expire afterward.
Use the POST /{threads-user-id}/threads endpoint to create a media container with the is_ghost_post parameter.
curl -i -X POST \ -d "media_type=TEXT" \ -d "text=<TEXT>"" \ -d "access_token=<ACCESS_TOKEN>"" \ -d "is_ghost_post=true" \ "https://graph.threads.net/v1.0/<THREADS_USER_ID>/threads"
{
"id": "<MEDIA_CONTAINER_ID>"
}
The request above creates a Threads media container that, once published, will create a ghost post.
You can publish using the returned Threads media container ID to create your ghost post.