Do you want a form that they can copy and duplicate? Is this within the modx manager or are they common (front-end) users?
If they will be user resources then, like a personal profile, the data would be limited to only that user, but there are other ways perhaps
Formit is good, how do you want them to be able to edit, just fill in new info or something else? If you can provide more info on what you need we can help understand the best way.
BTW, a big thing with Modx is, the core doesn’t do all that many extra functions. Users and several other basic functions, but not too many. This keeps the core secure and stable.
So, you will generally use quite a few Extras. Login for front-end users is a common one, and more specialized ones too.
You can also do custom snippets anywhere on your page to provide dynamic or other output