It is possible to do this, by using a condition. If you use the 'Content type Name' is equal to 'Folder', as your condition it will trigger when a folder is created. This will only work if you use 'When item is created' before this.
I can't find 'content type name' as and option when setting up the condition. has the name changed on newer versions? do you have a template or picture of your flow that you can share?
I also would like this trigger, and I couldn't get the condition - IsFolder workaround to help. SharePoint is requiring a List Name for the created item trigger--and the SP site I need this for has no lists. Also, I only want to trigger sending an email when a folder is created in a specific sub-folder of the Document Library (not ANY folder in the doc library).