Show hidden fields on 'thank you' page of autoresponder mail

It it possible to show hidden fields by conditions only after submission on the page or responder mail and not direct on the form?

I have different questions and every time a "Yes" is answered i want to display a extra text field but after only after submission and not on the form itself.

Because there are many different questions i can't do it with "CHANGE “THANK YOU” PAGE",  or i have to make more than 20 different thank you pages for all combinations.
I prefer also to do it in a autorespond mail, but is it possible at all?

Yes, you can actually do this with the Form Fields that you can use on the Thank You page or the Autoresponder email. I will attached a picture in order for you to see:

It is the number 4 on that image "Form Fields" there you will find your hidden fields in order to place them in there.

I believe this article will help you out too: https://www.jotform.com/help/26-Setting-Up-an-Autoresponder-Email

In the above guide, you can see how to include fields in Autoresponder email body. On the other hand, if you want to insert fields in Thank you page here is how to do that:

If you have any further questions please let us know.

Thank you!