Re-direct to a different URL if a field has been filled out

I’m looking in to if there is a way to re-direct my form to a different URL depending on if a field in the form has been filled out or not?

So if the field hasn’t been filled out then it would go https://www.example.com
and if it has been filled out then it would go to https://www.example.com/two.

I’m using on_sent_ok: "location.replace('https://example.com/');"to direct to the first URL but unsure how to re-direct to the second.

Anyone able to provide any tips?

https://www.ads-software.com/plugins/contact-form-7/