Aspiring freshman looking for advice.

I’m a freshman who’s dream schools to get into are UIUC, UC Berkeley, and UCLA.

My current classes are Honors English, Honors Algebra 2, Honors World History, and Honors Biology, with straight As in all of them.
I’m planning to continue with AP/Honors English, History, and Science classes wherever possible through high schol. In terms of math, I am taking Honors Precalc, then AP Calculus BC, and undecided for senior year.

I will have 3 years of Spanish and 3 years of Mandarin under my belt at graduation, along with three engineering courses and AP Computer Science.

My extracurriculars include swim team for 9 years, math team, and debate team.

My score on the school-administered Practice ACT was a 34. My current SAT score is a 2250. My GPA is currently 4.67 unweighted, 3.9 unweighted.

What can I do in the coming years to increase my chances of being accepted into these schools for Engineering?

you are certainly on the right track and, with your current trajectory, you will be an excellent candidate for those schools.