Xplore file manager.
Option called file sync.
Available in the free version. If you like it, do support the dev. Certain features are behind a paywall.
It can't create folders (atleast that I know of). But if you're on linux, you can create a folder daily and move the old one to one named by date.
ie.) Phone backs up to a folder called "Backup". Each day at midnight, the folder is renamed to "Backup - DDMMYYYY" and a new folder called "Backup" is created.
This is the best workaround I can think of.
But in this case, I don't think you'll be able to backup only missing files.