WARNING: The following contains spoilers for Episode 3 of Blade Runner: Black Lotus, "The Human Condition," airing on Adult Swim and now streaming on Crunchyroll.
Blade Runner: Black Lotus introduces Elle in Episode 1 as an amnesiac with no recollection of her life or identity. At best, she learns her combat skills and flashbacks are easily triggered by violent situations, but those are the only clues she has about herself. In Episode 2, she recognizes the face of Senator Bannister as a figure from her past and decides to confront him for answers. This encounter, however, doesn't go smoothly.
While meeting with Bannister at an illegal fighting ring, Elle learns she’s a replicant, which is why she's being hunted down to be killed. Elle refutes this, stating she’s human and impulsively killing Bannister. This last act puts her on the run, with LAPD hot on her trail. She is saved by Joseph who incapacitates her with a stun gun, which is where Episode 3, “The Human Condition,” picks up.
Episode 3 of Black Lotus opens with Elle waking in Joseph's flat. No longer certain of her human status, she asks him what a replicant is. In Joseph's explanation, replicants are corporate-manufactured artificial humans who exist to do slave labor unquestionably. This detail alone disturbs Elle, who starts to question if she is in fact a replicant since she has traits that far exceed those of a normal human. To confirm the truth, Joseph performs two tests on Elle.
The first test is to check for the presence of a serial number on Elle's right eye. If she has one, this would make her a Nexus-8 replicant, which has a longer lifespan than a Nexus-6 model. It would also explain why she was being hunted down, as Nexus-8 replicants' extended lifespans had led to backlash against them in the first place. Elle tests negative for the serial number, which eliminates her as a Nexus-8 model.
The second test Joseph performs on Elle is the Voight-Kampff test, which looks for contradictions between a person’s emotional reactions and their answers to emotional questions. Elle’s responses prove consistent with her emotions, which seems to eliminate her as a replicant entirely and confirm that she is indeed human. Despite the results of both tests, however, there is one thing neither is accounting for: that Elle possesses superhuman abilities and combat skills far exceeding that of a normal human.
With Elle seemingly having both human and replicant traits, this seems to imply she's a more highly advanced replicant model than a Nexus-8. The fact Elle has highly advanced combat skills, increased strength and peak endurance suggests she was designed for war. However, in order to prevent her from existing as a deadly killing machine, it's highly likely she was designed to possess human emotions so she could empathize with humans and make thoughtful decisions in combat. There is, of course, another flip side to giving a replicant human emotions: what if being driven by emotion makes her even more deadly than if she just followed orders?
This question is consistent with the events of Blade Runner: Black Out 2022, where angry supporters of the human supremacy movement accessed replicant registration databases to identify and kill replicants. This movement also prompted a Nexus-8 replicant built for combat called Iggy to destroy all replicant registration databases as well as the backups, resulting in the black out of 2022. The black out event is what led to the prohibition of replicant production and ended the Tyrell Corporation.
It took another decade for the Wallace Corporation to get approval to create a new model of replicant -- the decade Black Lotus is set in. If anything, it is highly likely Elle could be a Wallace Corporation replicant, which wouldn't follow the same standards as the Tyrell Corporation models. This would also account for why tests that were previously used on the Tyrell Corporation models wouldn't work on her.