1) Perform as best as you can in the interview.
2) Ask the recruiter explicitly what level the hiring committee decided to put you at. This generally won’t be negotiable since it depends on your interview performance.
3) Go on levels.fyi and look at the data points for such company/level, especially the recent ones, and try to stay towards the upper band of the spectrum.
4) If the offer that comes in is lower, politely ask your recruiter to match those you see online, referring them to the above link if needed. Confidently say that if they won’t be matched you will not be interested in pursuing the opportunity (just say this if it’s actually true, since there’s a real possibility they might call your bluff).
My split is exactly in line with what you can see on levels.fyi, so please refer to those data points.