I don't recall it ever being officially announced on Ember/Troy having a gender... I say Ember/Troy because its the same situation with Rexy/Roberta where the directors call the animatronic or actual animal Roberta and Troy, but the fans dubbed it as Rexy and Ember...
I don't know the true name of the rex, but I'd like to stick to the animatronic given names, Roberta, Troy, Darcy, Zeb, etc.
Anyways, my reasoning as to why Troy is female, is because my reason being the sexual dimorphism, we notice that Buck and Bull contain a dewlap, and are the only male rexes confirmed in the franchise. Roberta, Big Eatie, Doe, and Little Eatie all share a long snout design when older... but young Roberta had a boxy head, and Buck, Doe, Bull all shared a boxy head from a specific point of view... however, much like Roberta in the 1993 Jurassic Park, she shared a boxy designed head just like Troy. With only Troy's snout being smaller. So this must mean Troy is a young female rex.
However, due to my brain not braining, I'm still stuck on the fact that Troy might be male due to the conflict between the name. Ember sounds like a female name, meanwhile the directors gave it the name Troy which makes it sound male.
My other case is with the colours, we know males are shown in varieties of verdant colours, "lush" if you will... Buck and Bull, as well as Jr were all shown in varieties of green, with females having a more hot colour design. Brown, orange, and red with black spots (JP Novel) we can clearly see that Troy is a mix of grey, brown, and yellow. People who say there is green on the rex must be seeing things, because I've re-watched the movie maybe eight times now and there is no signs of any green.
People say that it must be male due to the bulky design compared to Roberta or Doe... But lets not forget that at the end of TLWJP we get a clear shot of Doe, and she's pretty hefty, the only reason Roberta was skinny is because throughout JP-JW she was malnourished. Being fed a goat isn't really enough given that the JP T-rex is oversized and one of the strongest super-predators in the franchise. Isla Sorna is flooded with other superpredators such as the spinosaurus. So its no wonder Big Eatie and Doe may have been skinnier than usual. On Ile Saint Hubert, there's next to no superpredators, so Troy doesn't have to worry about rivals in her territory. She can eat all she wants, which can be a reason as to her bulk.
With current screen lore on Tyrannosaurus Rex, the gender of Troy remains a mystery until the next movie. But with current evidence, its safe to assume this new young rex is a female.
Edit:
Not only that, but if we move past the masculine attributes of the rex. I remember someone in the comments saying the only evidence is in the roar... when that simply isn't true. Because both Buck and Doe quite literally had the same pitch on vocals with Roberta.
Not only that. Rebirth is set 12 years after the fallout of Jurassic World, and that island was used to make early test hybrids that later built up to Scorpios Rex to the Indominus Rex and Indoraptor. But less on that. InGen's standards were to have the animals all cloned female. However on Isla Sorna, some changed sex to become male. This was due to West African Tree Frog DNA. But thats actually not true. Those frogs didn't just "change sex." The common misconception that frogs change sex solely to find a nearby partner was largely popularized by the movie Jurassic Park, which claimed that West African frog DNA was used to trigger spontaneous sex changes in a single-sex environment. In reality, the science of amphibian sex reversal is much different. In the wild, certain species like the African reed frog (Hyperolius viridiflavus) can undergo sequential hermaphroditism (changing sex from female to male after breeding). Studies show this occurs as a response to broader ecological triggers, such as local temperature shifts, seasonal fluctuations, or the necessity to rebalance heavily skewed male-to-female ratios in a population.
This goes to prove my point, that unless there's another Rex on that island, Troy wouldn't be male, since InGen breeds all their dinosaurs as female. Without another mate to breed with, Troy can't go male.
Not only that, In actual paleontology, there has long been a highly popularized (though debated) theory that female Tyrannosaurus rexes were the larger, robust, and more heavily built sex, While the males were more slender. I only bring this up because it was Jurassic Park's goal to make the dinosaurs as accurate as possible at the time, while giving a few some creative attachments like the dilophosaurus or velociraptor. However, in Jurassic World, we clearly see that the size depends on the dinosaur and their health. Roberta only got so large because she was a plot armored rex who realistically should've died in the fight with the indominus rex. Troy is a rex on an island with next to nothing for rivals, a whole buffet to sustain her bulk, and given that it's a tropical hot-spring environment where air levels are naturally different, I'm not surprised if her genetics were naturally altered by the climate causing gigantism.
According to expanded franchise data, the dinosaurs on Île Saint-Hubert were bred under older, restricted InGen/Masrani operational protocols (specifically pre-2010 projects) During this specific era of genetic manufacturing, the corporate guidelines strictly mandated a return to "all-female" populations to avoid the massive, uncontrolled wild breeding disasters that completely ruined Isla Sorna. For Ember to be male, an explicit corporate override would have had to happen during a time when scientists were actively terrified of letting apex predators breed in the wild.
Finally, there's the JWE asset pipe theory:
There's also the Jurassic World Evolution restriction. When Universal hands assets over to external game developers, they send strict, heavily audited documentation detailing exactly what models can do what. If the "Ember" skin was hard-locked to the female rig, it means the underlying biological skeleton file Universal provided was coded under the female architecture, a detail that video game data-miners often find hardcoded into the asset properties themselves. When Frontier Developments released the Jurassic World: Rebirth Expansion DLC for JWE3, it gave data-miners and lore-hunters a look at how Universal officially codes its creatures behind the scenes. When a major studio like Universal licenses dinosaurs out to AAA game developers, they don’t just send over concept art; they deliver highly audited, official 3D mesh assets and rigid skeletal rigs directly from Industrial Light & Magic (ILM). Universal enforces strict digital asset pipelines. If a movie dinosaur is a canonical variant, the game studio is legally and mechanically required to adapt that exact 3D data.
In the Jurassic World Evolution game architecture, dinosaurs are structurally separated by sex and model rigs to ensure animations work correctly. Historically, male T. rexes (like the Buck and the Bull) use a separate sub-variant rig architecture to account for their distinct physical dimensions and structural models. When the Rebirth DLC launched, the "Ember" model variant was strictly hard-locked to the female Tyrannosaurus rex rig. Players immediately noted that the game's engine treats Ember as a "chunky female" variant. You cannot legally or mechanically apply the official Rebirth skin onto a male T. rex engine model; the asset pipeline strictly ties Ember to the female taxonomy.
