Strange question but okay.
If I am in a store and on my iphone want to join a network I go to settings and join.
The only time I can be forced anywhere is when I open the browser.
So just choosing the wifi network doesnt guarantee anything will be viewed.
If you mean when someone opens the browser can they be redirected elsewhere?
Not sure, if I type in
https://address, can that be redirected to a different address?
Perhaps there is some DNS redirection that can be done, but I dont have the technical knowledge to help you.