In all seriousness why do you think Jacob and Sam ended up with opposite body types in the show? They never really justified it themselves and neither have the writers but it’s clearly deliberate. I just don’t think they are necessarily looking at it through yaoi vision like we are. Or maybe they are.
I think it comes down to how they interpret their characters and choices they make to inhabit their characters better. I don’t think they’re looking at it through yaoi vision too like I don’t think anyone sat down to say “ok so Lestat has to be bigger than Louis” lol but I do think the writing does influence how they interpret their characters. Like you said, the writers never really justified it, hell iirc Sam even said that Rolin initially didn’t even care if he had short hair as Lestat ToT but because they are actors who have to inhabit the character/navigate the environment as their character I think the deliberate choices they make about their physicality just help them do their job better. We all know about how Jacob said his inspiration for Louis is Eartha Kitt and Grace Jones, but iirc he also described Louis’ movement as “lizard-like”, so we can understand that he sees Louis as elegant and graceful as well as fluid and flexible which I think match with how he is written and portrayed on-screen. On the other hand, Lestat has always been written as imposing and loud, someone who is larger-than-life. This feature of Lestat’s character is not only shown through the writing and the language used to talk about him, but in other aspects of the show as well. Carol Cutshall has said that the costuming for Lestat is meant to emphasize the width of his shoulder (seen through how in s1 Lestat is put in a lot of double-breasted suits, a cut that broadens your shoulder with a boxy silhouette. Interestingly, this type of suit is never seen on Louis). A lot of shots are framed and angled so that Lestat is taller and more intimidating, and Lestat gets that extreme close up treatment that emphasizes his jawline and expressions a lot. All of which to say, even if their character descriptions are not written explicitly and the writers never justified it outright, I think the writing choices do influence how the actors interpret a character which in turn influence how they choose to alter their physicality to portray that character.