Deleted texts

Assuming you do not house your messages in iCloud, they are saved on your iPhone backup that was created while the messages existed. Restore the backup to retrieve the messages.

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

If you are using iCloud Messages, you cannot. If you are not, then the only way to recover a deleted text is if you have a recent backup made when the text message was still on the iPhone. No backup, no restore.