Show with ?url=topic

I’m not sure. It might work as explained here https://contactform7.com/getting-default-values-from-the-context/ but I haven’t tried it yet.

So, for your example, you could have the condition set up to show/hide a certain group from the URL, like so:

Form:

[select* show-group-1 default:get "Yes" "No"]
[group-1]I'm visible now![/group-1]

Conditions:
if [show-group-1] equals "Yes" then show [group-1]

And then call this url: http://someurl.com/contact?show-group-1=Yes

Could you please give it a try and report back here? Thanks!