I see the issue. Yeah, there ARE multiple canon sources that DO contradict one another. That's been a problem in the franchise from the beginning of time, especially for the Tyrannosaurus since it's the face of the franchise and thus gets the most exposure and stats, and generally Rexy's image is used even if it's for a general estimate. In regard to the animatronics, Rexy's full-size animatronic from JP was said by Stan Winston in Dinosaur Filmography to actually be about 37 feet, not the commonly embellished 40 feet. That leads to a problem when it comes to TLW's Tyrannosaurus animatronics being 37 feet without tails, because obviously those tails are going to add at least another 10 feet, and we know Rexy is and always has been the biggest individual of her species. There's no way she was 10+ feet smaller than the parents from TLW, going by animatronic size. That no-tail thing as a whole makes this problematic because we have to guess how much those tails would add to the length of the animal, and it would surely be more than all of the canon estimates we've been given, which is just wrong.
I was once told by Jack Ewins that the Jurassic World size for Rexy was a rounded down estimate, which makes sense because if you look at a lot of estimates for the species over the years, it's basically been 40 feet regardless if it's for Rexy herself or not. Even the DPG graphic using 40 feet for the Tyrannosaurus, which had Rexy's image of course, Ewins said it was the "rounded down species average" (paraphrasing) and not for Rexy specifically, while saying 44 feet was indeed Rexy's true length. The Arcadia manifest also had Rexy at 44 feet long and 17 feet tall.
Because of all of these estimates from various sources, I've had to ask people like Jack Ewins what takes precedence and what's even going on with all these contradictions. Out-of-universe, it's because the people hired to do this stuff simply don't know the ins-and-outs of every InGen dinosaur like us more hardcore fans do, or like the DPG they're trying to compromise and use a basic middle-ground estimate like that 40-foot number that's usually tossed around for the Tyrannosaurus. We seem to be the ones that find it significant whether it's 40 feet or 44 feet, but most casual people don't think it's a big enough difference to lose sleep over, and that's where we get the problem from.
Basically, Ewins has confirmed Rexy's size for us in lieu of all the contradicting sources, he's confirmed whenever we see 40 feet for Rexy it's a general estimate and not her true size, he's confirmed the Spinosaurus in JP3 was fully grown (I don't think he's ever commented on the specific size of it, though), and since he and his team are working with Colin Trevorrow right now, it seems they're basically in charge of what's going on with the animal sizes. Spielberg too, of course, but he's more of a digital model alteration guy.