I just checked my app directory and found that I already have this app, I think it’s the workflow settings.
Which makes sense, because that’s what I did for now.
I read this post and followed it:
For example if I want to have all files uploaded to the “Photo” folder tagged with the tag “photo”,
I add an invisible tag “photo-parent” to the “Photo” folder itself,
Then I go to workflow, add rule
If File system tag is tagged with “photo-parent”, tag the file with the tag “photo”
And it works!