That depends. I have friends that take HL Math and Physics, and they are VERY strong in those fields even prior to IB.
If Math is not your strong suit, I don’t suggest doing it. But by all means, practice can make perfect. Just be sure that you know what you’re headed into. Similarly, for HL Physics. Those two are one of the hardest courses in the IB.
However, you noted that you are majoring in CS. That would mean you need a heavy math load. It is up to you.