CS is currently the most competitive major there is.
There are lots of majors related to it (information science, informatics, computing, UX, etc).
If the only IB science your school offers is biology then yes you’re right - you’d need to have bio, chem, physics; calc bc should be followed with discrete math (dual enrollment/PSEO/running start?) If possible.
If you had both world and us history then sure take Psychology, especially since it can include a lot of bio.