windows - I am trying to batch create multiple text files in subfolders

I am creating .txt files with a list of the file names within a given subfolder. I have around 100 subfolders within each of the 18 main folders, so I would like batch create the .txt files to save time if possible.
For each subfolder, I am using the following code

dir /b > filenames.txt

Can I do this in larger batches from all subfolders within each main folder?

Thanks!