I don't know/remember offhand all the details that I've seen posted about it, but I think it was something like:
-Warner wants Bugs to have a girlfriend/female counterpart, to use in merchandise and I guess to also add a more prominent female to the cast roster (so it's not surprising that she's been used for the past 20+ years in various Looney Tunes stuff, she was meant to last beyond that movie)
-Original sketches have what would become Lola (she had different proto names, including dumb shit like "Bunni Bunny") as a more tomboyish/athletic female rabbit, less of an obvious "hairstyle" and no bunny boobies etc. Apparently that got some complaints that it looked too much like Bugs hitting on a teenage boy, McDonald's or someone said they wouldn't do merchandise with her looking like that, and so they sexed her up into the form she's known for today.
-Lola seems to have had slightly more of a role/personality in earlier visions of the film than in the final one. Maybe slight changes to her design and the production of the film itself kept resulting in her scenes getting overhauled. She was apparently sort of added to the film's final version pretty last-minute, which is why she's barely there even when she's supposed to be and mostly just interacts with Bugs>I don't know if the sexiness itself was deliberately played up beyond how she already looks, but I remember seeing stuff about the cool new GIRL who's great at basketball, she challenges Bugs and he falls for her, "don't ever call her doll," and so on, making it seem like she had a huge role in the movie, when that's pretty much all she does
-Also, yeah, I think some actual furries, as in involved in the fandom, were involved with her design