Hello,
Is there a setting where I can limit the user's input to just 3 choices on a checkbox field.
No, it would likely require some Javascript or some magic with hidden fields that are using formulas. The easiest way would be to make this 3 separate required radio button fields instead of 1 checkbox field.
You could create a field that counts the checkboxes that are checked with this code:
=IF(Checkbox.Choice_1,1,0)+IF(Checkbox.Choice_2,1,0)+IF(Checkbox.Choice_3,1,0)+IF(Checkbox.Choice_4,1,0)+IF(Checkbox.Choice_5,1,0)
Then as soon as that value is greater than 2, the checkbox field is disabled with field rules:
So the form would look like this before the value is greater than 2:
And as soon as it is 3, the field would be disabled:
And you can hide the how many checkboxes are checked field.
But, if you want people to be able to change their mind, you would need something more that would allow that field to be cleared of all checkboxes.