Hi! And welcome to the forum
First, the approach to this depends on how realistic do you want it to be or how much control you have over the use of the prototype.
If you are the one presenting the prototype or you have agreed on a script/journey, you can always fake it so it would behave as intended.
If you are planning to test this with users and have no control over what they’d interact with, you’d need a more functional/realistic approach.
For option 1, I’d simply link the last checkbox to tell the button to go to its active state, then when you present it (or someone follows the agreed script), the button will activate and give the impression that it was linked to the checked statuses of the checkboxes (but it’s not).
For option 2, you’d need to create as many screens or states as combinations are possible, this changes dramatically based on how many checkboxes do you have, with 3 checkboxes, there’s a total of 8 different states, but if you have 5 checkboxes then we are talking about more than 30.
I hope this helps, let me know if you have any questions!