Some of it is about pacing. AP Bio and AP Chem are both a lot of memorization. Will you have enough time to spend on these classes if you take them at the same time?
Also, consider your teachers. Are they known to be good? Too rigorous? Not teach? My kid’s AP Bio teacher didn’t teach 3 of the 8 units during online/COVID. This left my kid to self learn these units. It was sheer agony. I can’t imagine if they had to do that plus learn AP Chem at the same time.
What did you take in 9th? What are your career goals? Will you major in STEM?