I want to ask a question on my form that says "choose your top 3 choices from this list of 10 things." I'm sure there's a way to do this but how?
Here's what I would recommend:
Open your form builder and add a Choice - Checkboxes field to your form.
Select Show Custom Error - When in the field settings. Click the Advanced Editor tab and insert the following expression:
=(FieldName.Count() != 3)
Make sure to write a custom error message that appears when someone doesn't select the corrct number of options ("Please select 3 choices.")