Go to a library or a friend or wherever you can access a computer. Even buy a prepaid phone with the least data you can get so it’s cheap, and use that to locate your phone.

Just for the sake of saying it, in this age it’s rather rare to find someone who has only one Internet connected device whatsoever. If that’s the case really, and it’s your phone, then you really need to have extra precaution. Get a cheap backup phone like an Android you can get for like $10 even a really good one. I buy and sell these they’re very cheap these days if you don’t need the best. Don’t have to have a cellular plan on it just keep it at home and you can get it from wherever you keep it and go to anywhere there’s wifi.