Restaurant or Fast Food.
I think Sonic is the only fast food place I can think of that serves cherry soda with cherries in it.
Dairy Queen will add them.
Does it need to be a particular menu item? Because I doubt we’ll find a national chain that would devote the space.
But I’d also hope a place that had cherries at all might stir some into a drink (or side of ranch) with a polite request at a reasonable time. Besides places with bar cherries (Olive Garden, Chilis, TGI-bees, etc), pancake restaurants with fruit like IHOP & Denny’s.
And there are some high-end chains that I’d expect an effortless accommodation like Fogo or Gibson’s. Is Hard Rock Casino a restaurant chain?
Johnny Rockets
Braum’s
Genghis Grill.
When I ordered Coke with grenadine at Applebee’s, they’d always put a cherry in it.
Tough guys drink wild cherry phosphate. It’s made from syrup of cherry tree bark, which contains a teeny amount of cyanide, plus acid phosphate, an additive that gives it extra bite. An old soda fountain perennial that fell out of fashion. Too bad. Look it up and you’ll want to try it.
That reminds me of when I was a little girl and my parents would let me have a Shirley Temple if we ate out at a “fancy” restaurant. The only difference between the two drinks was that Roy was made with cola and Shirley used lemon-lime soda.