Unless you own a major real estate development firm that she is going to inherit, she should not plan her math schedule based on a mild interest she has as she turns 16.
Even if she manages to arrive on campus 28 months from now still intending to major in real estate development, more than 50% of students think about changing majors and depending on the school 30-40% actually do change.
Selective colleges like Penn and NYU are going to want to see 4 solid years of math in HS. These days that almost always means AP Calc AB.
Very few people are naturally good at math. Many of those who think they are in the 10th grade learn otherwise before they are though with school.
The biggest point of studying math is to learn how to learn and struggle and learn difficult concepts. If a student graduates never having bothered to do this, they aren't going to get very far.
https://singjupost.com/transcript-barbara-oakley-on-learning-how-to-learn-at-tedxoaklanduniversity/
As the transcript suggests, math is very sequential. Most people as soon as they miss a section decide they are "bad at math" and that is the end.
The limited number of things DD can do during the pandemic limitations is a great opportunity to take a practice (free online) PSAT/SAT and use that to figure out what parts she has missed.
Then use Khan academy to fill in the gaps. If this process is done meticulously, she will be an entirely different math student next fall. Even if she just plays around with it for an hour a week until September, it will help her PSAT/SAT scores.