Set photos show Chris Hemsworth sporting a new look in Endgame after the Avengers failed to undo Thanos' snap was one of the movie's big early surprises, which had been smartly hidden by the marketing. While there was some division over whether it simply made his weight-gain into a joke or not, there was a real attempt at tackling the character's PTSD within there. Endgame saw Thor going off with the Guardians of the Galaxy, and there's since been a question of whether or not Fat Thor would return in Thor 4.
That question has seemingly been answered. Back in November 2020, Hemsworth posted a picture of a massive body transformation, getting completely ripped in preparation for Thor: Love and Thunder production starting. With filming getting underway, set photos revealed Hemsworth in a new Thor costume, looking at lot like the Thunderstrike character from the comics, and certainly a far cry from the Fat Thor of Avengers: Endgame.
Since the various images all highlight Hemsworth being jacked, and the set photos show him with the Guardians of the Galaxy - whom he is likely with at the beginning of the movie - then it suggests that from this will be his appearance from the get-go, leaving no room for Fat Thor to appear. That may well be true, but given Endgame kept Fat Thor a surprise, then Love and Thunder may simply be repeating the trick for now. It wouldn't necessarily need to go as far as Endgame, either, since these are just the initial set photos; when the marketing begins proper, it could reveal Fat Thor again, which would be a great hook for a trailer. The Guardians of the Galaxy's role in Love and Thunder looks to be a sizable one, so it's similarly plausible that the film does open with Thor still looking like he did in Endgame, before transforming later on, and that would be important for its narrative.
It makes sense that Love and Thunder wouldn't want to stick with Fat Thor throughout the entire movie, because it's continuing a thread from an Avengers movie, but at the same time, it'd also be fitting to address it in some way. Rather than just being a joke, Fat Thor was reflective of his psyche, of his past arrogance, and his greatest failure. There's a lot of character work still to be done in showing how he gets from being Fat Thor to the more traditional god of thunder type figure who'll be seen in Thor 4, and it would be a real shame not to explore that or show how it happens, especially because it should be key to his role with the Guardians.
The Thor: Ragnarok's only problems was that it undercut its emotion for sake of comedy; having Fat Thor in the movie and showing that journey can deliver both comic relief and Guardians-weirdness, while still telling a heartfelt story that nicely resolves Thor's PTSD arc.
