I know you can visit some theme parks at certain times of year to avoid many children, however what I mean are theme parks built more for imaginative and fun-loving adults.
Take some of the park rides you might find in family theme parks that appeal to both adults and children, but instead of avoiding elements that may confuse/frighten children, they’re allowed to get more detailed or whatever may be more fun for people. Fwiw I’m aware of some smaller scale themed venues (particularly some horror-related ones), but I feel like I’m blanking on any obvious larger scale ones.
In several of the parks, yes! Hell, getting drunk off of “drinks from around the world” at Walt Disney World’s EPCOT is a popular theme for adult guests nowadays. However, I’ll mention that Disneyland is still quite restrictive (though their neighboring park, California Adventure, is not and fully embrace alcohol sales).