“Ant-Man,” released eight years ago, was a comic-book movie that almost inadvertently used its hyper-miniaturized cowboy-on-ant-back superhero as a metaphor for what a tiny place the film itself occupied in the MCU. “Ant-Man and the Wasp” (2018) was a bit less small. The director, Peyton Reed, who had a background in human comedy (“Down with Love,” “Bring It On”), expanded the sequel into a puckish fantasy of scale, with characters and objects popping back and forth in size, though the result was still more amusing than momentous. Paul Rudd’s nice-guy divorced dad turned badass metallic bug Scott Lang may have been an official Avenger, but that still didn’t give him more than a flyweight significance.

Now, though, with “Ant-Man and the Wasp: Quantumania,” the “Ant-Man” series has gone Full Marvel. The new movie takes place almost entirely in the Quantum Realm, a mutating sub-atomic sphere that exists outside our space-time continuum. It’s essentially an anything-goes FX playground that resembles a psychedelic album cover crossed with a 21st-century update of “Fantastic Voyage” (lots of things that look like corpuscles). What it feels like, most directly, is a planet from one of the later “Star Wars” films, with a few old-school Cantina vibes. (You could make a case that the George Lucas prequels represented the takeover of “Star Wars” by the Cantina.)

In “Quantumania,” there are sci-fi “Alice in Wonderland” forests, full of manta-ray moths and tiny tentacled suns as well as characters who resemble giant stalks of broccoli, walking Jell-O sculptures and glowing TV consoles. There’s an army of super-ant saviors. There is, of course, a hooded rebel alliance, as well as a cosmic genocidal megalomaniac — Kang the Conqueror (Jonathan Majors), a supervillain who made his debut in the comics in 1963 and looks like he’s being set up to dominate the MCU until 2063. There’s Bill Murray, coiffed like a debauched George Washington, as a former rebel who now works for Kang. There’s Corey Stoll’s Darren, the corporate baddie from the first “Ant-Man,” who returns in the form of M.O.D.O.K., a huge malevolent head encased in tin-pot armor with insect hands and legs. The character is another comics stalwart, but given the pointedly cheeky way his scenes are staged, you might say that Reed has merged his sense of humor with a dash of Taika Waititi’s dada absurdism.

Reed, at the same time, is out to conjure the deadly gravitas of an “Avengers” epic. Vast populations, whole strands of the multiverse, are at stake. Yet since “Quantumania” claims to be a film about the manipulation of matter, we should probably ask: With everything going on in this movie, does any of it actually matter?

Yes and no. “Quantumania” is a state-of-the-art exercise in world-building, and in the neverending fantasy world (namely, ours) that was built by J.R.R. Tolkien and Dungeons & Dragons and “Star Wars” and “Harry Potter” and sandbox video games and Lego assembly kits that can number 10,000 pieces, it’s worth noting how axiomatic it is that when people today use the phrase “world-building,” they mean it as a high compliment. Another world! Another fun place for us to play in!

“Quantumania” is fun, as well as bedazzling, relentless and numbing, then fun again just when you think you’ve had enough; all of that gets mashed together. The Marvel films have never pretended to be stand-alone entities, yet I’ve rarely encountered a Marvel adventure that’s this busy with a do-or-die saving-the-cosmos plot that feels this much like it exists simply to set up the next dozen chapters of something. But that’s what happens when you’re launching Phase 5 of the Marvel takeover of movie entertainment. “Quantumania” is no cheat (it sucks you in, hooks your eyeballs, wrings you out), but if this is what Phase 5 looks like, God save us from Phases 6, 7 and 8.

Scott’s science-prodigy daughter, Cassie (Kathryn Newton), now a plucky young woman of 18, has built some sort of meta telescope in the basement. Within minutes, the device sucks everyone to the Quantum Realm — Scott and Cassie, along with Scott’s bug-superhero partner and paramour, Hope van Dyne (Evangeline Lilly), and Hope’s parents, the crusty physicist and former S.H.I.E.L.D. agent Hank Pym (Michael Douglas) and the original Wasp, Janet van Dyne (Michelle Pfeiffer), who in the previous film was rescued after having spent 30 years down there. It turns out that she was doing more than passing the time watching Netflix. She was there when Kang first showed up as a stranded traveler — but, in fact, he was already an exile who’d been kicked to the Quantum Realm to halt his path of destruction. Janet blew up the core of Kang’s quantum device, which saved the multiverse. But she’s still regarded by the rebels with mistrust. And Kang hasn’t gone away; his designs have just been put on hold.