If you want to create bulk folders using Google Sheets, this is the perfect tool. The tool is part of the Plus Tools* sidebar.
Create new Google Sheet and add your main folder in column A and subfolders in columns B, C, D, etc. Add the folder ID where you want the folders to be created.
If you don’t add a folder ID, the folders in column A will be created directly in your Drive root.
*this is a paid feature.