Surely an instagrammer who meets is an escort
Perhaps, or perhaps not in their own minds, or perhaps not at all, money wasn't mentioned for a start so if any girls did meet it wouldn't be vastly different to Tinder, the lines become blurred, a girl from Tinder who's looking for a date but is short of money but would like to try that new restaurant? There's always an element of ego, girls in skimpy clothes on Insta are loving the thought of men lusting after them it's not a massive leap the think that she wouldn't crave that same worship in the flesh, perhaps the only difference is an element of choice, there'll be some right ugly mugs out punting and if they have £100 in their hand they can have a shag, maybe that's not so easy with an Insta girl, has a girl from Insta even met a man? Is not a serious question. Would she meet for cash is the real question, find one you like the look of and send her a message that you've got 2 tickets for the whole Monaco GP weekend staying in the best hotel and I suspect you'll get a bite.
So, to the original OP, do Insta girls meet? Of course they do, I would think the popular ones get 100 propositions a day, but they won't just meet anybody, you'll probably need to look like the male equivalent of them or have cash coming out of your ears, it's not so different to the real world.