To simplify, you have to sync to a tertiary location first, then to the destination. If you don't mind, why are you syncing folders on the same device?
I'm syncing within device as I like to keep my original photos on the phone, although I back up to the cloud. I use my phone for work and home and sometimes take photos that I want to save directly to the computer at full resolution (cloud sync is a lower resolution via google photos). It takes ages to load a folder with 1000s of photos though, so I want to sync all my photos to Camera_old then delete all photos in Camera. That way I can keep the Camera folder relatively small. I don't trust simply cut and pasting so many files.
If I'm going to need to do this in three steps via the computer I'm probably going to just stop keeping a copy on the phone, so the problem kind of solves itself!