This Loki season 2 theory suggests OB could actually be the next MCU big bad

gamesradar.com:

Loki season 2 may be hiding the villain of Avengers: Secret Wars in plain sight, according to a new theory. 

"Was rewatching episode 5 of Loki last night and had a fun thought – what if Ouroboros or a variant of him that we haven’t met yet is going to be our 'Beyonder,' and the events of Secret Wars are him playing out a sci-fi fantasy of his own design after Kang is defeated?" theorized one Redditor. 

"He’s a seemingly very accomplished theoretical physicist who was able to decipher science generations beyond him and create the TemPad in 19 months, so who knows what he could accomplish once he has access to future tech. Plus his love of sci-fi mixed with his apparent inability to write a story people like might lead him to go off the chain a bit."

In Loki season 2 episode 5, OB (and the rest of the TVA) has been reset to his original life as Dr. A.D. Doug, who, as well as being a theoretical physicist, is also a struggling sci-fi novelist.

As for the Beyonder, he's a villain from the Secret Wars comic book series. He's an all-powerful being who becomes fascinated with the heroes and villains of Earth. He summons a ragtag bunch, including the Avengers, X-Men, and Doctor Doom, to a warzone known as Battleworld and gets them to fight it out, promising to grant the wishes of the winning side. 

There have been several theories that OB, the TVA employee played by Ke Huy Quan, isn't who he appears to be – including that his glasses may be disguising his true identity. "What if the glasses are there as a red herring, to make OB seem more normal/mortal/human. Something maybe even OB himself adopted at some point, specifically for that purpose," a Reddit user wrote. 

A movie titled Avengers: Secret Wars is set to release in May