The IP in the parks thing has been going on for awhile, certainly. Like one of my criticisms of the Cars area is that it’s a decades old IP that could already be fading with Gen Alpha. (My son is a preschooler and while this is anecdotal, I don’t see kids that age talking about it, wearing the shirts, etc.) 
With the merch - princess and princess adjacent characters certainly got merch, as did sequels (Toy Story, Cars, Wreck It Ralph, Finding Dory, Frozen, Incredibles, Star Wars, Marvel, Spider Verse although not sure who has merch rights to that). Looking back, I’m actually surprised to see how many of the movies of the past decade/s were part of a pre-existing franchise. For movies like Coco or Big Hero 6 I honestly can’t remember. So maybe Wish didn’t start the trend, but I’m fairly certain it didn’t help.